Science.gov

Sample records for environment electron transport

  1. A Deterministic Transport Code for Space Environment Electrons

    NASA Technical Reports Server (NTRS)

    Nealy, John E.; Chang, C. K.; Norman, Ryan B.; Blattnig, Steve R.; Badavi, Francis F.; Adamczyk, Anne M.

    2010-01-01

    A deterministic computational procedure has been developed to describe transport of space environment electrons in various shield media. This code is an upgrade and extension of an earlier electron code. Whereas the former code was formulated on the basis of parametric functions derived from limited laboratory data, the present code utilizes well established theoretical representations to describe the relevant interactions and transport processes. The shield material specification has been made more general, as have the pertinent cross sections. A combined mean free path and average trajectory approach has been used in the transport formalism. Comparisons with Monte Carlo calculations are presented.

  2. A deterministic computational procedure for space environment electron transport

    NASA Astrophysics Data System (ADS)

    Nealy, John E.; Chang, C. K.; Norman, Ryan B.; Blattnig, Steve R.; Badavi, Francis F.; Adamczyk, Anne M.

    2010-08-01

    A deterministic computational procedure for describing the transport of electrons in condensed media is formulated to simulate the effects and exposures from spectral distributions typical of electrons trapped in planetary magnetic fields. The primary purpose for developing the procedure is to provide a means of rapidly performing numerous repetitive transport calculations essential for electron radiation exposure assessments for complex space structures. The present code utilizes well-established theoretical representations to describe the relevant interactions and transport processes. A combined mean free path and average trajectory approach is used in the transport formalism. For typical space environment spectra, several favorable comparisons with Monte Carlo calculations are made which have indicated that accuracy is not compromised at the expense of the computational speed.

  3. A Deterministic Computational Procedure for Space Environment Electron Transport

    NASA Technical Reports Server (NTRS)

    Nealy, John E.; Chang, C. K.; Norman, Ryan B.; Blattnig, Steve R.; Badavi, Francis F.; Adamcyk, Anne M.

    2010-01-01

    A deterministic computational procedure for describing the transport of electrons in condensed media is formulated to simulate the effects and exposures from spectral distributions typical of electrons trapped in planetary magnetic fields. The primary purpose for developing the procedure is to provide a means of rapidly performing numerous repetitive transport calculations essential for electron radiation exposure assessments for complex space structures. The present code utilizes well-established theoretical representations to describe the relevant interactions and transport processes. A combined mean free path and average trajectory approach is used in the transport formalism. For typical space environment spectra, several favorable comparisons with Monte Carlo calculations are made which have indicated that accuracy is not compromised at the expense of the computational speed.

  4. Electron-transfer-induced and phononic heat transport in molecular environments

    NASA Astrophysics Data System (ADS)

    Chen, Renai; Craven, Galen T.; Nitzan, Abraham

    2017-09-01

    A unified theory of heat transport in environments that sustain intersite phononic coupling and electron hopping is developed. The heat currents generated by both phononic transport and electron transfer between sites characterized by different local temperatures are calculated and compared. Using typical molecular parameters we find that the electron-transfer-induced heat current can be comparable to that of the standard phononic transport for donor-acceptor pairs with efficient bidirectional electron transfer rates (relatively small intersite distance and favorable free-energy difference). In most other situations, phononic transport is the dominant heat transfer mechanism.

  5. Transport of Space Environment Electrons: A Simplified Rapid-Analysis Computational Procedure

    NASA Technical Reports Server (NTRS)

    Nealy, John E.; Anderson, Brooke M.; Cucinotta, Francis A.; Wilson, John W.; Katz, Robert; Chang, C. K.

    2002-01-01

    A computational procedure for describing transport of electrons in condensed media has been formulated for application to effects and exposures from spectral distributions typical of electrons trapped in planetary magnetic fields. The procedure is based on earlier parameterizations established from numerous electron beam experiments. New parameterizations have been derived that logically extend the domain of application to low molecular weight (high hydrogen content) materials and higher energies (approximately 50 MeV). The production and transport of high energy photons (bremsstrahlung) generated in the electron transport processes have also been modeled using tabulated values of photon production cross sections. A primary purpose for developing the procedure has been to provide a means for rapidly performing numerous repetitive calculations essential for electron radiation exposure assessments for complex space structures. Several favorable comparisons have been made with previous calculations for typical space environment spectra, which have indicated that accuracy has not been substantially compromised at the expense of computational speed.

  6. Nonequilibrium electron transport in a hybrid superconductor-normal metal entangler in a dissipative environment

    NASA Astrophysics Data System (ADS)

    Bubanja, Vladimir; Yamamoto, Mayumi; Iwabuchi, Shuichi

    2016-11-01

    We consider a three-terminal Cooper-pair splitting device with a superconducting electrode tunnel coupled to two normal metal electrodes. We employ the Nambu-Gor'kov and Schwinger-Keldysh formalisms to describe the nonequilibrium transport properties of the device for arbitrary transmissions of the barriers and for a general electromagnetic environment. We derive the analytic expressions for the current and the nonlocal differential conductance, and analyze the limits of clean and dirty superconductivity.

  7. Electronics for Extreme Environments

    NASA Technical Reports Server (NTRS)

    Patel, J. U.; Cressler, J.; Li, Y.; Niu, G.

    2001-01-01

    Most of the NASA missions involve extreme environments comprising radiation and low or high temperatures. Current practice of providing friendly ambient operating environment to electronics costs considerable power and mass (for shielding). Immediate missions such as the Europa orbiter and lander and Mars landers require the electronics to perform reliably in extreme conditions during the most critical part of the mission. Some other missions planned in the future also involve substantial surface activity in terms of measurements, sample collection, penetration through ice and crust and the analysis of samples. Thus it is extremely critical to develop electronics that could reliably operate under extreme space environments. Silicon On Insulator (SOI) technology is an extremely attractive candidate for NASA's future low power and high speed electronic systems because it offers increased transconductance, decreased sub-threshold slope, reduced short channel effects, elimination of kink effect, enhanced low field mobility, and immunity from radiation induced latch-up. A common belief that semiconductor devices function better at low temperatures is generally true for bulk devices but it does not hold true for deep sub-micron SOI CMOS devices with microscopic device features of 0.25 micrometers and smaller. Various temperature sensitive device parameters and device characteristics have recently been reported in the literature. Behavior of state of the art technology devices under such conditions needs to be evaluated in order to determine possible modifications in the device design for better performance and survivability under extreme environments. Here, we present a unique approach of developing electronics for extreme environments to benefit future NASA missions as described above. This will also benefit other long transit/life time missions such as the solar sail and planetary outposts in which electronics is out open in the unshielded space at the ambient space

  8. An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. I. Model and validation

    SciTech Connect

    Hegde, Ganesh Povolotskyi, Michael; Kubis, Tillmann; Klimeck, Gerhard; Boykin, Timothy

    2014-03-28

    Semi-empirical Tight Binding (TB) is known to be a scalable and accurate atomistic representation for electron transport for realistically extended nano-scaled semiconductor devices that might contain millions of atoms. In this paper, an environment-aware and transferable TB model suitable for electronic structure and transport simulations in technologically relevant metals, metallic alloys, metal nanostructures, and metallic interface systems are described. Part I of this paper describes the development and validation of the new TB model. The new model incorporates intra-atomic diagonal and off-diagonal elements for implicit self-consistency and greater transferability across bonding environments. The dependence of the on-site energies on strain has been obtained by appealing to the Moments Theorem that links closed electron paths in the system to energy moments of angular momentum resolved local density of states obtained ab initio. The model matches self-consistent density functional theory electronic structure results for bulk face centered cubic metals with and without strain, metallic alloys, metallic interfaces, and metallic nanostructures with high accuracy and can be used in predictive electronic structure and transport problems in metallic systems at realistically extended length scales.

  9. An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. I. Model and validation

    NASA Astrophysics Data System (ADS)

    Hegde, Ganesh; Povolotskyi, Michael; Kubis, Tillmann; Boykin, Timothy; Klimeck, Gerhard

    2014-03-01

    Semi-empirical Tight Binding (TB) is known to be a scalable and accurate atomistic representation for electron transport for realistically extended nano-scaled semiconductor devices that might contain millions of atoms. In this paper, an environment-aware and transferable TB model suitable for electronic structure and transport simulations in technologically relevant metals, metallic alloys, metal nanostructures, and metallic interface systems are described. Part I of this paper describes the development and validation of the new TB model. The new model incorporates intra-atomic diagonal and off-diagonal elements for implicit self-consistency and greater transferability across bonding environments. The dependence of the on-site energies on strain has been obtained by appealing to the Moments Theorem that links closed electron paths in the system to energy moments of angular momentum resolved local density of states obtained ab initio. The model matches self-consistent density functional theory electronic structure results for bulk face centered cubic metals with and without strain, metallic alloys, metallic interfaces, and metallic nanostructures with high accuracy and can be used in predictive electronic structure and transport problems in metallic systems at realistically extended length scales.

  10. Electron transporting semiconducting polymers in organic electronics.

    PubMed

    Zhao, Xingang; Zhan, Xiaowei

    2011-07-01

    Significant progress has been achieved in the preparation of semiconducting polymers over the past two decades, and successful commercial devices based on them are slowly beginning to enter the market. However, most of the conjugated polymers are hole transporting, or p-type, semiconductors that have seen a dramatic rise in performance over the last decade. Much less attention has been devoted to electron transporting, or n-type, materials that have lagged behind their p-type counterparts. Organic electron transporting materials are essential for the fabrication of organic p-n junctions, organic photovoltaic cells (OPVs), n-channel organic field-effect transistors (OFETs), organic light-emitting diodes (OLEDs) and complementary logic circuits. In this critical review we focus upon recent developments in several classes of electron transporting semiconducting polymers used in OLEDs, OFETs and OPVs, and survey and analyze what is currently known concerning electron transporting semiconductor architecture, electronic structure, and device performance relationships (87 references).

  11. The influence of leaf anatomy on the internal light environment and photosynthetic electron transport rate: exploration with a new leaf ray tracing model

    PubMed Central

    Xiao, Yi; Tholen, Danny; Zhu, Xin-Guang

    2016-01-01

    Leaf photosynthesis is determined by biochemical properties and anatomical features. Here we developed a three-dimensional leaf model that can be used to evaluate the internal light environment of a leaf and its implications for whole-leaf electron transport rates (J). This model includes (i) the basic components of a leaf, such as the epidermis, palisade and spongy tissues, as well as the physical dimensions and arrangements of cell walls, vacuoles and chloroplasts; and (ii) an efficient forward ray-tracing algorithm, predicting the internal light environment for light of wavelengths between 400 and 2500nm. We studied the influence of leaf anatomy and ambient light on internal light conditions and J. The results show that (i) different chloroplasts can experience drastically different light conditions, even when they are located at the same distance from the leaf surface; (ii) bundle sheath extensions, which are strips of parenchyma, collenchyma or sclerenchyma cells connecting the vascular bundles with the epidermis, can influence photosynthetic light-use efficiency of leaves; and (iii) chloroplast positioning can also influence the light-use efficiency of leaves. Mechanisms underlying leaf internal light heterogeneity and implications of the heterogeneity for photoprotection and for the convexity of the light response curves are discussed. PMID:27702991

  12. The influence of leaf anatomy on the internal light environment and photosynthetic electron transport rate: exploration with a new leaf ray tracing model.

    PubMed

    Xiao, Yi; Tholen, Danny; Zhu, Xin-Guang

    2016-11-01

    Leaf photosynthesis is determined by biochemical properties and anatomical features. Here we developed a three-dimensional leaf model that can be used to evaluate the internal light environment of a leaf and its implications for whole-leaf electron transport rates (J). This model includes (i) the basic components of a leaf, such as the epidermis, palisade and spongy tissues, as well as the physical dimensions and arrangements of cell walls, vacuoles and chloroplasts; and (ii) an efficient forward ray-tracing algorithm, predicting the internal light environment for light of wavelengths between 400 and 2500nm. We studied the influence of leaf anatomy and ambient light on internal light conditions and J The results show that (i) different chloroplasts can experience drastically different light conditions, even when they are located at the same distance from the leaf surface; (ii) bundle sheath extensions, which are strips of parenchyma, collenchyma or sclerenchyma cells connecting the vascular bundles with the epidermis, can influence photosynthetic light-use efficiency of leaves; and (iii) chloroplast positioning can also influence the light-use efficiency of leaves. Mechanisms underlying leaf internal light heterogeneity and implications of the heterogeneity for photoprotection and for the convexity of the light response curves are discussed.

  13. Electronic transport in polycrystalline graphene.

    PubMed

    Yazyev, Oleg V; Louie, Steven G

    2010-10-01

    Most materials in available macroscopic quantities are polycrystalline. Graphene, a recently discovered two-dimensional form of carbon with strong potential for replacing silicon in future electronics, is no exception. There is growing evidence of the polycrystalline nature of graphene samples obtained using various techniques. Grain boundaries, intrinsic topological defects of polycrystalline materials, are expected to markedly alter the electronic transport in graphene. Here, we develop a theory of charge carrier transmission through grain boundaries composed of a periodic array of dislocations in graphene based on the momentum conservation principle. Depending on the grain-boundary structure we find two distinct transport behaviours--either high transparency, or perfect reflection of charge carriers over remarkably large energy ranges. First-principles quantum transport calculations are used to verify and further investigate this striking behaviour. Our study sheds light on the transport properties of large-area graphene samples. Furthermore, purposeful engineering of periodic grain boundaries with tunable transport gaps would allow for controlling charge currents without the need to introduce bulk bandgaps in otherwise semimetallic graphene. The proposed approach can be regarded as a means towards building practical graphene electronics.

  14. Electron transport in bipyridinium films.

    PubMed

    Raymo, Françisco M; Alvarado, Robert J

    2004-01-01

    Bipyridinium dications are versatile building blocks for the assembly of functional materials. In particular, their reliable electrochemical response has encouraged the design of electroactive films. Diverse and elegant experimental strategies to coat metallic and semiconducting electrodes with bipyridinium compounds have, in fact, emerged over the past two decades. The resulting interfacial assemblies span from a few nanometers to several micrometers in thickness. They incorporate from a single molecular layer to large collections of entangled polymer chains. They transport electrons efficiently from the electrode surface to the film/solution interface and vice versa. Electron self-exchange between and the physical diffusion of the bipyridinium building blocks conspire in defining the charge transport properties of these fascinating electroactive assemblies. Often, the matrix of electron-deficient bipyridinium dications can be exploited to entrap electron-rich analytes. Electrostatic interactions promote the supramolecular association of the guests with the surface-confined host matrix. Furthermore, chromophoric sites can be coupled to the bipyridinium dications to produce photosensitive arrays capable of harvesting light and generating current. Thus, thorough investigations on the fundamental properties of these functional molecule-based materials can lead to promising applications in electroanalysis and solar energy conversion, while contributing to advances in the basic understanding of electron transport in interfacial assemblies.

  15. Designing Electronic Collaborative Learning Environments

    ERIC Educational Resources Information Center

    Kirschner, Paul; Strijbos, Jan-Willem; Kreijns, Karel; Beers, Pieter Jelle

    2004-01-01

    Electronic collaborative learning environments for learning and working are in vogue. Designers design them according to their own constructivist interpretations of what collaborative learning is and what it should achieve. Educators employ them with different educational approaches and in diverse situations to achieve different ends. Students use…

  16. Electronic Transport in Ultrathin Heterostructures.

    DTIC Science & Technology

    1981-10-01

    well (?QW), metalorganic chemical vapor deposition (40CVD), superlattice disorder, two-dimensional electron gas structures, quantum well ...Emission from Quantum Wells IV. Laser Emission from GaAlAs/Gaas Superlattices V. Diffusion-Enhanced Disorder of Superlattices VI. Transport...Properties of MOCVD MQW Structures - 7. r: - r ’ " IT M : , --- *I i- 1.0 INTRODUCTION The recent development of sophisticaed and well controlled epitaxial

  17. Electron Transport in Hall Thrusters

    NASA Astrophysics Data System (ADS)

    McDonald, Michael Sean

    Despite high technological maturity and a long flight heritage, computer models of Hall thrusters remain dependent on empirical inputs and a large part of thruster development to date has been heavily experimental in nature. This empirical approach will become increasingly unsustainable as new high-power thrusters tax existing ground test facilities and more exotic thruster designs stretch and strain the boundaries of existing design experience. The fundamental obstacle preventing predictive modeling of Hall thruster plasma properties and channel erosion is the lack of a first-principles description of electron transport across the strong magnetic fields between the cathode and anode. In spite of an abundance of proposed transport mechanisms, accurate assessments of the magnitude of electron current due to any one mechanism are scarce, and comparative studies of their relative influence on a single thruster platform simply do not exist. Lacking a clear idea of what mechanism(s) are primarily responsible for transport, it is understandably difficult for the electric propulsion scientist to focus his or her theoretical and computational tools on the right targets. This work presents a primarily experimental investigation of collisional and turbulent Hall thruster electron transport mechanisms. High-speed imaging of the thruster discharge channel at tens of thousands of frames per second reveals omnipresent rotating regions of elevated light emission, identified with a rotating spoke instability. This turbulent instability has been shown through construction of an azimuthally segmented anode to drive significant cross-field electron current in the discharge channel, and suggestive evidence points to its spatial extent into the thruster near-field plume as well. Electron trajectory simulations in experimentally measured thruster electromagnetic fields indicate that binary collisional transport mechanisms are not significant in the thruster plume, and experiments

  18. Electronic transport in unconventional superconductors

    SciTech Connect

    Graf, M.J.

    1998-12-31

    The author investigates the electron transport coefficients in unconventional superconductors at low temperatures, where charge and heat transport are dominated by electron scattering from random lattice defects. He discusses the features of the pairing symmetry, Fermi surface, and excitation spectrum which are reflected in the low temperature heat transport. For temperatures {kappa}{sub B}T {approx_lt} {gamma} {much_lt} {Delta}{sub 0}, where {gamma} is the bandwidth of impurity induced Andreev states, certain eigenvalues become universal, i.e., independent of the impurity concentration and phase shift. Deep in the superconducting phase ({kappa}{sub B}T {approx_lt} {gamma}) the Wiedemann-Franz law, with Sommerfeld`s value of the Lorenz number, is recovered. He compares the results for theoretical models of unconventional superconductivity in high-{Tc} and heavy fermion superconductors with experiment. The findings show that impurities are a sensitive probe of the low-energy excitation spectrum, and that the zero-temperature limit of the transport coefficients provides an important test of the order parameter symmetry.

  19. Harsh environments electronics : downhole applications.

    SciTech Connect

    Vianco, Paul Thomas

    2011-03-01

    The development and operational sustainment of renewable (geothermal) and non-renewable (fossil fuel) energy resources will be accompanied by increasingly higher costs factors: exploration and site preparation, operational maintenance and repair. Increased government oversight in the wake of the Gulf oil spill will only add to the cost burden. It is important to understand that downhole conditions are not just about elevated temperatures. It is often construed that military electronics are exposed to the upper limit in terms of extreme service environments. Probably the harshest of all service conditions for electronics and electrical equipment are those in oil, gas, and geothermal wells. From the technology perspective, advanced materials, sensors, and microelectronics devices are benefificial to the exploration and sustainment of energy resources, especially in terms of lower costs. Besides the need for the science that creates these breakthroughs - there is also a need for sustained engineering development and testing. Downhole oil, gas, and geothermal well applications can have a wide range of environments and reliability requirements: Temperature, Pressure, Vibration, Corrosion, and Service duration. All too frequently, these conditions are not well-defifined because the application is labeled as 'high temperature'. This ambiguity is problematic when the investigation turns to new approaches for electronic packaging solutions. The objective is to develop harsh environment, electronic packaging that meets customer requirements of cost, performance, and reliability. There are a number of challenges: (1) Materials sets - solder alloys, substrate materials; (2) Manufacturing process - low to middle volumes, low defect counts, new equipment technologies; and (3) Reliability testing - requirements documents, test methods and modeling, relevant standards documents. The cost to develop and sustain renewable and non-renewable energy resources will continue to escalate

  20. Regulation of Photosynthetic Electron Transport and Photoinhibition

    PubMed Central

    Roach, Thomas; Krieger-Liszkay, Anja Krieger

    2014-01-01

    Photosynthetic organisms and isolated photosystems are of interest for technical applications. In nature, photosynthetic electron transport has to work efficiently in contrasting environments such as shade and full sunlight at noon. Photosynthetic electron transport is regulated on many levels, starting with the energy transfer processes in antenna and ending with how reducing power is ultimately partitioned. This review starts by explaining how light energy can be dissipated or distributed by the various mechanisms of non-photochemical quenching, including thermal dissipation and state transitions, and how these processes influence photoinhibition of photosystem II (PSII). Furthermore, we will highlight the importance of the various alternative electron transport pathways, including the use of oxygen as the terminal electron acceptor and cyclic flow around photosystem I (PSI), the latter which seem particularly relevant to preventing photoinhibition of photosystem I. The control of excitation pressure in combination with the partitioning of reducing power influences the light-dependent formation of reactive oxygen species in PSII and in PSI, which may be a very important consideration to any artificial photosynthetic system or technical device using photosynthetic organisms. PMID:24678670

  1. Electronic Transport in Graphene Heterostructures

    NASA Astrophysics Data System (ADS)

    Young, Andrea F.; Kim, Philip

    2011-03-01

    The elementary excitations of monolayer graphene, which behave as massless Dirac particles, make it a fascinating venue in which to study relativistic quantum phenomena. One notable example is Klein tunneling, a phenomena in which electrons convert to holes to tunnel through a potential barrier. However, the omnipresence of charged impurities in substrate-supported samples keep the overall charge distribution nonuniform, obscuring much of this "Dirac" point physics in large samples. Using local gates, one can create tunable heterojunctions in graphene, isolating the contribution of small regions of the samples to transport. In this review, we give an overview of quantum transport theory and experiment on locally gated graphene heterostructures, with an emphasis on bipolar junctions.

  2. Mars Transportation Environment Definition Document

    NASA Technical Reports Server (NTRS)

    Alexander, M. (Editor)

    2001-01-01

    This document provides a compilation of environments knowledge about the planet Mars. Information is divided into three catagories: (1) interplanetary space environments (environments required by the technical community to travel to and from Mars); (2) atmospheric environments (environments needed to aerocapture, aerobrake, or use aeroassist for precision trajectories down to the surface); and (3) surface environments (environments needed to have robots or explorers survive and work on the surface).

  3. Inner Radiation Belt Representation of the Energetic Electron Environment: Model and Data Synthesis Using the Salammbo Radiation Belt Transport Code and Los Alamos Geosynchronous and GPS Energetic Particle Data

    NASA Technical Reports Server (NTRS)

    Friedel, R. H. W.; Bourdarie, S.; Fennell, J.; Kanekal, S.; Cayton, T. E.

    2004-01-01

    The highly energetic electron environment in the inner magnetosphere (GEO inward) has received a lot of research attention in resent years, as the dynamics of relativistic electron acceleration and transport are not yet fully understood. These electrons can cause deep dielectric charging in any space hardware in the MEO to GEO region. We use a new and novel approach to obtain a global representation of the inner magnetospheric energetic electron environment, which can reproduce the absolute environment (flux) for any spacecraft orbit in that region to within a factor of 2 for the energy range of 100 KeV to 5 MeV electrons, for any levels of magnetospheric activity. We combine the extensive set of inner magnetospheric energetic electron observations available at Los Alamos with the physics based Salammbo transport code, using the data assimilation technique of "nudging". This in effect input in-situ data into the code and allows the diffusion mechanisms in the code to interpolate the data into regions and times of no data availability. We present here details of the methods used, both in the data assimilation process and in the necessary inter-calibration of the input data used. We will present sample runs of the model/data code and compare the results to test spacecraft data not used in the data assimilation process.

  4. Coordinating Electron Transport Chains to an Electron Donor.

    PubMed

    Villegas, Carmen; Wolf, Maximilian; Joly, Damien; Delgado, Juan Luis; Guldi, Dirk M; Martín, Nazario

    2015-10-16

    Two electron transport chains (2 and 3) featuring two fullerenes with different electron acceptor strengths have been synthesized, characterized, and coordinated to a light harvesting/electron donating zinc porphyrin. Electrochemical assays corroborate the redox gradients along the designed electron transport chains, and complementary absorption and fluorescence titrations prove the assembly of ZnP-2 and ZnP-3 hybrids.

  5. Electronic transport in nanoscale structures

    NASA Astrophysics Data System (ADS)

    Lagerqvist, Johan

    In this dissertation electronic transport in nanoscale structures is discussed. An expression for the shot noise, a fluctuation in current due to the discreteness of charge, is derived directly from the wave functions of a nanoscale system. Investigation of shot noise is of particular interest due to the rich fundamental physics involved. For example, the study of shot noise can provide fundamental insight on the nature of electron transport in a nanoscale junction. We report calculations of the shot noise properties of parallel wires in the regime in which the interwire distance is much smaller than the inelastic mean free path. The validity of quantized transverse momenta in a nanoscale structure and its effect on shot noise is also discussed. We theoretically propose and show the feasibility of a novel protocol for DNA sequencing based on the electronic signature of single-stranded DNA while it translocates through a nanopore. We find that the currents for the bases are sufficiently different to allow for efficient sequencing. Our estimates reveal that sequencing of an entire human genome could be done with very high accuracy in a matter of hours, e.g., orders of magnitude faster than present techniques. We also find that although the overall magnitude of the current may change dramatically with different detection conditions, the intrinsic distinguishability of the bases is not significantly affected by pore size and transverse field strength. Finally, we study the ability of water to screen charges in nanopores by using all-atom molecular dynamics simulations coupled to electrostatic calculations. Due to the short length scales of the nanopore geometry and the large local field gradient of a single ion, the energetics of transporting an ion through the pore is strongly dependent on the microscopic details of the electric field. We show that as long as the pore allows the first hydration shell to stay intact, e.g., ˜6 nearby water molecules, the electric field

  6. Electron transport in ferromagnetic nanostructures

    NASA Astrophysics Data System (ADS)

    Lee, Sungbae

    As the size of a physical system decreases toward the nanoscale, quantum mechanical effects such as the discretization of energy levels and the interactions of the electronic spins become readily observable. To understand what happens within submicrometer scale samples is one of the goals of modern condensed matter physics. Electron transport phenomena drew a lot of attention over the past two decades or so, not only because quantum corrections to the classical transport theory, but also they allow us to probe deeply into the microscopic nature of the system put to test. Although a significant amount of research was done in the past and thus extended our understanding in this field, most of these works were concentrated on simpler examples. Electron transport in strongly correlated systems is still a field that needs to be explored more thoroughly. In fact, experimental works that have been done so far to characterize coherence physics in correlated systems such as ferromagnetic metals are far from conclusive. One reason ferromagnetic samples draw such attention is that there exist correlations that lead to excitations (e.g. spin waves, domain wall motions) not present in normal metals, and these new environmental degrees of freedom can have profound effects on decoherence processes. In this thesis, three different types of magnetic samples were examined: a band ferromagnetism based metallic ferromagnet, permalloy, a III-V diluted ferromagnetic semiconductor with ferromagnetism from a hole-mediated exchange interaction, and magnetite nanocrystals and films. The first observation of time-dependent universal conductance fluctuations (TD-UCF) in permalloy is presented and our observations lead to three major conclusions. First, the cooperon contribution to the conductance is suppressed in this material. This is consistent with some theoretical expectations, and implies that weak localization will be suppressed as well. Second, we see evidence that domain wall motion

  7. Electron Transport in Short Peptide Single Molecules

    NASA Astrophysics Data System (ADS)

    Cui, Jing; Brisendine, Joseph; Ng, Fay; Nuckolls, Colin; Koder, Ronald; Venkarataman, Latha

    We present a study of the electron transport through a series of short peptides using scanning tunneling microscope-based break junction method. Our work is motivated by the need to gain a better understanding of how various levels of protein structure contribute to the remarkable capacity of proteins to transport charge in biophysical processes such as respiration and photosynthesis. We focus here on short mono, di and tri-peptides, and probe their conductance when bound to gold electrodes in a native buffer environment. We first show that these peptides can bind to gold through amine, carboxyl, thiol and methyl-sulfide termini. We then focus on two systems (glycine and alanine) and show that their conductance decays faster than alkanes terminated by the same linkers. Importantly, our results show that the peptide bond is less conductive than a sigma carbon-carbon bond. This work was supported in part by NSF-DMR 1507440.

  8. Environic implications of lighter than air transportation

    NASA Technical Reports Server (NTRS)

    Horsbrugh, P.

    1975-01-01

    The advent of any new system of transportation must now be reviewed in the physical context and texture of the landscape. Henceforward, all transportation systems will be considered in respect of their effects upon the environment to ensure that they afford an environic asset as well as provide an economic benefit. The obligations which now confront the buoyancy engineers are emphasized so that they may respond to these ethical and environic urgencies simultaneously with routine technical development.

  9. Design of an eMonitor system to transport electronic patient care report (ePCR) information in unstable MobileIP wireless environment.

    PubMed

    Giovanni, Mazza G; Shenvi, Rohit; Battles, Marcie; Orthner, Helmuth F

    2008-11-06

    The eMonitor is a component of the ePatient system; a prototype system used by emergency medical services (EMS) personnel in the field to record and transmits electronic patient care report (ePCR) information interactively. The eMonitor component allows each Mobile Data Terminal (MDT) on an unreliable Cisco MobileIP wireless network to securely send and received XML messages used to update patient information to and from the MDT before, during and after the transport of a patient.

  10. Phonon limited electronic transport in Pb

    NASA Astrophysics Data System (ADS)

    Rittweger, F.; Hinsche, N. F.; Mertig, I.

    2017-09-01

    We present a fully ab initio based scheme to compute electronic transport properties, i.e. the electrical conductivity σ and thermopower S, in the presence of electron-phonon interaction. We explicitly investigate the \

  11. Vapor Transport to Indoor Environments

    EPA Science Inventory

    The indoor environment is an important microenvironment for human exposure to chemicals, both because people spend most of their time indoors and because chemicals are often at higher concentrations indoors versus outdoors. This chapter reviews the major components in estimating ...

  12. Vapor Transport to Indoor Environments

    EPA Science Inventory

    The indoor environment is an important microenvironment for human exposure to chemicals, both because people spend most of their time indoors and because chemicals are often at higher concentrations indoors versus outdoors. This chapter reviews the major components in estimating ...

  13. Maryland House Environment & Transportation Committee Visit

    NASA Image and Video Library

    2016-11-15

    Center Director Chris Scolese welcomed the Maryland House Environment & Transportation Committee to Goddard on November 15, 2016. The group visited the James Webb Space Telescope JWST and then they toured the Robotics Operations Facility.

  14. Maryland House Environment & Transportation Committee Visit

    NASA Image and Video Library

    2016-11-15

    Center Director Chris Scolese welcomed the Maryland House Environment & Transportation Committee to Goddard on November 15, 2016. The group visited the James Webb Space Telescope JWST and saw the mirrors open, then they toured the Robotic Operations Center - ROC.

  15. Coupled electron-photon radiation transport

    SciTech Connect

    Lorence, L.; Kensek, R.P.; Valdez, G.D.; Drumm, C.R.; Fan, W.C.; Powell, J.L.

    2000-01-17

    Massively-parallel computers allow detailed 3D radiation transport simulations to be performed to analyze the response of complex systems to radiation. This has been recently been demonstrated with the coupled electron-photon Monte Carlo code, ITS. To enable such calculations, the combinatorial geometry capability of ITS was improved. For greater geometrical flexibility, a version of ITS is under development that can track particles in CAD geometries. Deterministic radiation transport codes that utilize an unstructured spatial mesh are also being devised. For electron transport, the authors are investigating second-order forms of the transport equations which, when discretized, yield symmetric positive definite matrices. A novel parallelization strategy, simultaneously solving for spatial and angular unknowns, has been applied to the even- and odd-parity forms of the transport equation on a 2D unstructured spatial mesh. Another second-order form, the self-adjoint angular flux transport equation, also shows promise for electron transport.

  16. Numerical Solution of 3D Poisson-Nernst-Planck Equations Coupled with Classical Density Functional Theory for Modeling Ion and Electron Transport in a Confined Environment

    NASA Astrophysics Data System (ADS)

    Meng, Da; Zheng, Bin; Lin, Guang; Sushko, Maria L.

    2014-11-01

    We have developed efficient numerical algorithms for solving 3D steady-state Poisson-Nernst-Planck (PNP) equations with excess chemical potentials described by the classical density functional theory (cDFT). The coupled PNP equations are discretized by a finite difference scheme and solved iteratively using the Gummel method with relaxation. The Nernst-Planck equations are transformed into Laplace equations through the Slotboom transformation. Then, the algebraic multigrid method is applied to efficiently solve the Poisson equation and the transformed Nernst-Planck equations. A novel strategy for calculating excess chemical potentials through fast Fourier transforms is proposed, which reduces computational complexity from $O(N^2)$ to $O(N\\log N)$, where $N$ is the number of grid points. Integrals involving the Dirac delta function are evaluated directly by coordinate transformation, which yields more accurate results compared to applying numerical quadrature to an approximated delta function. Numerical results for ion and electron transport in solid electrolyte for lithium-ion (Li-ion) batteries are shown to be in good agreement with the experimental data and the results from previous studies.

  17. Numerical Solution of 3D Poisson-Nernst-Planck Equations Coupled with Classical Density Functional Theory for Modeling Ion and Electron Transport in a Confined Environment

    SciTech Connect

    Meng, Da; Zheng, Bin; Lin, Guang; Sushko, Maria L.

    2014-08-29

    We have developed efficient numerical algorithms for the solution of 3D steady-state Poisson-Nernst-Planck equations (PNP) with excess chemical potentials described by the classical density functional theory (cDFT). The coupled PNP equations are discretized by finite difference scheme and solved iteratively by Gummel method with relaxation. The Nernst-Planck equations are transformed into Laplace equations through the Slotboom transformation. Algebraic multigrid method is then applied to efficiently solve the Poisson equation and the transformed Nernst-Planck equations. A novel strategy for calculating excess chemical potentials through fast Fourier transforms is proposed which reduces computational complexity from O(N2) to O(NlogN) where N is the number of grid points. Integrals involving Dirac delta function are evaluated directly by coordinate transformation which yields more accurate result compared to applying numerical quadrature to an approximated delta function. Numerical results for ion and electron transport in solid electrolyte for Li ion batteries are shown to be in good agreement with the experimental data and the results from previous studies.

  18. Electron transport in a coaxial Hall discharge

    NASA Astrophysics Data System (ADS)

    Meezan, Nathan Benjamin

    Coaxial Hall discharges---also known as Hall thrusters, stationary plasma thrusters, and closed drift accelerators---are cross-field plasma sources under development for space propulsion applications. The Hall thruster is an electrostatic rocket that uses a magnetic field perpendicular to the thrust axis to shape the accelerating potential distribution. Electrons must cross magnetic field lines to sustain the discharge. The Hall discharge exhibits "anomalous" electron transport, meaning that the electron current through the device is higher than that predicted by simple calculations. This thesis explores two competing mechanisms of anomalous electron transport---fluctuation-induced transport and near-wall conductivity. A series of investigations, experimental and theoretical, are used to identify if plasma fluctuations and/or near-wall conductivity is responsible for anomalous electron transport in coaxial Hall discharges. Using classical equations as a framework for quantifying transport, experimental data from several plasma diagnostic techniques are used to demonstrate the presence of anomalous transport in the Hall discharge channel at several operating voltages. Electrostatic probe and optical emission experiments are used to measure the plasma oscillations inside the Hall discharge channel. The probe data are used with a statistical theory of turbulent transport to predict the transport coefficient based on the oscillation amplitude. The resulting transport coefficient shows remarkable agreement with the experimentally measured coefficient, strongly suggesting that plasma density oscillations are responsible for anomalous transport. To explore the effect of electron-wall collisions on the plasma, the Boltzmann equation is solved for the EEDF in the discharge channel. For the resultant EEDFs, which are depleted at high energy, the electron-wall collision frequencies and secondary electron yields are found to be too low to be significant to cross

  19. MUCH Electronic Publishing Environment: Principles and Practices.

    ERIC Educational Resources Information Center

    Min, Zheng; Rada, Roy

    1994-01-01

    Discusses the electronic publishing system called Many Using and Creating Hypermedia (MUCH). The MUCH system supports collaborative authoring; reuse; formatting and printing; management; hypermedia publishing and delivery; and interchange. This article examines electronic publishing environments; the MUCH environment; publishing activities; and…

  20. Electron Transport in Water Vapour

    NASA Astrophysics Data System (ADS)

    Kawaguchi, Satoru; Satoh, Kohki; Itoh, Hidenori

    2015-09-01

    Sets of electron collision cross sections for water vapour previously reported are examined by comparing calculated electron swarm parameters with measured parameters. Further, reliable cross section set of water vapour is estimated by the electron swarm method using Monte Carlo simulation to ensure the accuracy of the swarm parameter calculation. The values of an electron drift velocity, a longitudinal diffusion coefficient, and an effective ionisation coefficient calculated from Yousfi and Benabdessadok's set and those calculated from Itikawa and Mason's set do not necessarily agree with measured data. A new cross section set of water vapour, which consists of three kinds of rotational excitation, two kinds of vibrational excitation, three kinds of electron attachment, twenty-six kinds of electronic excitation, and six kinds of ionisation cross sections, and an elastic collision cross section, is estimated, and an anisotropic electron scattering for elastic and rotational excitation collision is considered. The swarm parameters calculated from the estimated cross section set is in good agreement with measured data in a wide range of reduced electric field.

  1. Particle Transport in Pure Electron Plasmas.

    NASA Astrophysics Data System (ADS)

    Kriesel, J. M.; Driscoll, C. F.

    1998-10-01

    At UCSD we confine pure-electron plasmas in Penning-Malmberg traps, which consist of cylindrical electrodes in an axial magnetic field (B ~ 100G). The trap is under ultra-high vacuum (10-10 Torr) so that transport due to electron-neutral collisions is negligible. Instead, cross-field particle transport is due to electron-electron collsions or from interactions with external fields. A plasma in one of our traps is roughly cylindrical in shape and rotates about its own axis due to the E x B drift from the space-charge field. Electron-electron collisions bring the plasma to a thermal equilibrium state of rigid rotation and uniform temperature. We find that the transport is driven by shears in the rotation velocity, and measure a coefficient of viscosity which is as much as 10,000 times larger than classical theory. This transport is driven by long-range ``E × B drift Coulomb collisions'' with impact parameters on the order of a Debye length rather than a cyclotron radius, as in classical theory. In our plasmas λD >> r_c, and O'Neil and Dubin have developed theories(Daniel H.E. Dubin, Phys. Plasmas 5), 1688 (1998) of transport in this regime. In addition to this work, I will also present measurements on the transport due to externally applied fields. The scalings provide insight into the overall confinement properties of our traps.

  2. Study of Electron Transport and Amplification in Diamond

    SciTech Connect

    Ben-Zvi, Ilan; Muller, Erik

    2015-01-05

    The development of the Diamond Amplified Photocathode (DAP) has produced significant results under our previous HEP funded efforts both on the fabrication of working devices and the understanding of the underlying physics governing its performance. The results presented here substantiate the use of diamond as both a secondary electron amplifier for high-brightness, high-average-current electron sources and as a photon and particle detector in harsh radiation environments. Very high average current densities (>10A/cm2) have been transported through diamond material. The transport has been measured as a function of incident photon energy and found to be in good agreement with theoretical models. Measurements of the charge transport for photon energies near the carbon K-edge (290 eV for sp3 bonded carbon) have provided insight into carrier loss due to diffusion; modeling of this aspect of charge transport is underway. The response of diamond to nanosecond x-ray pulses has been measured; in this regime the charge transport is as expected. Electron emission from hydrogenated diamond has been measured using both electron and x-ray generated carriers; a gain of 178 has been observed for electron-generated carriers. The energy spectrum of the emitted electrons has been measured, providing insight into the electron affinity and ultimately the thermal emittance. The origin of charge trapping in diamond has been investigated for both bulk and surface trapping

  3. Transport experiments with Dirac electrons

    NASA Astrophysics Data System (ADS)

    Checkelsky, Joseph George

    This thesis presents transport experiments performed on solid state systems in which the behavior of the charge carriers can be described by the Dirac equation. Unlike the massive carriers in a typical material, in these systems the carriers behave like massless fermions with a photon-like dispersion predicted to greatly modify their spin and charge transport properties. The first system studied is graphene, a crystalline monolayer of carbon arranged in a hexagonal lattice. The band structure calculated from the hexagonal lattice has the form of the massless Dirac Hamiltonian. At the charge neutral Dirac point, we find that application of a magnetic field drives a transition to an insulating state. We also study the thermoelectric properties of graphene and find that the states near the Dirac point have a unique response compared to those at higher charge density. The second system is the 3D topological insulator Bi2Se3, where a Dirac-like dispersion for states on the 2D surface of the insulating 3D crystal arises as a result of the topology of the 3D bands and time reversal symmetry. To access the transport properties of the 2D states, we suppress the remnant bulk conduction channel by chemical doping and electrostatic gating. In bulk crystals we find strong quantum corrections to transport at low temperature when the bulk conduction channel is maximally suppressed. In microscopic crystals we are able better to isolate the surface conduction channel properties. We identify in-gap conducting states that have relatively high mobility compared to the bulk and exhibit weak anti-localization, consistent with predictions for protected 2D surface states with strong spin-orbit coupling.

  4. The Electron Transport Chain: An Interactive Simulation

    ERIC Educational Resources Information Center

    Romero, Chris; Choun, James

    2014-01-01

    This activity provides students an interactive demonstration of the electron transport chain and chemiosmosis during aerobic respiration. Students use simple, everyday objects as hydrogen ions and electrons and play the roles of the various proteins embedded in the inner mitochondrial membrane to show how this specific process in cellular…

  5. The Electron Transport Chain: An Interactive Simulation

    ERIC Educational Resources Information Center

    Romero, Chris; Choun, James

    2014-01-01

    This activity provides students an interactive demonstration of the electron transport chain and chemiosmosis during aerobic respiration. Students use simple, everyday objects as hydrogen ions and electrons and play the roles of the various proteins embedded in the inner mitochondrial membrane to show how this specific process in cellular…

  6. [Transport, environment and health. 2008 SESPAS Report].

    PubMed

    Ballester, Ferran; Peiró, Rosanna

    2008-04-01

    Motor road transport has increased exponentially in the last few years. To a large extent, mobility is an essential element in the organization of society, but, until recently, the implications of chosen forms of transport for health and the environment have not been considered. In this chapter we review the negative impact of current forms of transport on health in terms of traffic injuries, climate change, atmospheric contamination, noise, and interference with daily activities and exercise, such as impediments to walking or cycling. Some possible interventions related to the instruments available in public health and other fields are proposed. Issues deserving further research are highlighted. Some examples in Spain and other countries are described. Recommendations are made on the need to reduce the use of private cars and to develop segmented routes and areas of quiet traffic connected in the cities and among nearby towns to promote walking are cycling. One major goal in current public policies should be to develop and maintain a public transport system that is safe, cheap and faster and less polluting than private transport. These interventions would help to achieve a change in current modes of transport and would lead to a healthier population and a more sustainable environment.

  7. Electron transport through single carbon nanotubes

    SciTech Connect

    Schenkel, Thomas; Chai, G.; Heinrich, H.; Chow, L.; Schenkel, T.

    2007-08-01

    We report on the transport of energetic electrons through single, well aligned multi-wall carbon nanotubes (CNT). Embedding of CNTs in a protective carbon fiber coating enables the application of focused ion beam based sample preparation techniques for the non-destructive isolation and alignment of individual tubes. Aligned tubes with lengths of 0.7 to 3 mu m allow transport of 300 keV electrons in a transmission electron microscope through their hollow cores at zero degree incident angles and for a misalignment of up to 1 degree.

  8. Feminist Interventions in Electronic Environments.

    ERIC Educational Resources Information Center

    Hocks, Mary E.

    1999-01-01

    Notes that feminist interventions are communicative acts that bring attention to shifting power relations within a specific discursive context. Argues that enacting feminist interventions in online environments changes the online community's identity and narrow sense of audience, and that creating feminist multimedia helps ensure a more human,…

  9. Multidimensional Deterministic Electron Transport Calculations

    DTIC Science & Technology

    1992-05-01

    inlllnlnilinlmmm nMI MII n~lA - Is - -The SMART scattering matrix is not tied to a particular angular flux distribution . -There is considerable numerical...Both expressions are derived by performing an uncollided electron balance over the i’th path length cell. The uncollided flux is then distributed to the...OIS1UTInOIAVALAIT Y STAIEMENT LDIOSTRIUTION CODE Approved for public release; distribution unlimited. 13. A8STRACTO"d noww Fast and accurate techniques for

  10. Auxiliary electron transport pathways in chloroplasts of microalgae.

    PubMed

    Peltier, Gilles; Tolleter, Dimitri; Billon, Emmanuelle; Cournac, Laurent

    2010-11-01

    Microalgae are photosynthetic organisms which cover an extraordinary phylogenic diversity and have colonized extremely diverse habitats. Adaptation to contrasted environments in terms of light and nutrient's availabilities has been possible through a high flexibility of the photosynthetic machinery. Indeed, optimal functioning of photosynthesis in changing environments requires a fine tuning between the conversion of light energy by photosystems and its use by metabolic reaction, a particularly important parameter being the balance between phosphorylating (ATP) and reducing (NADPH) power supplies. In addition to the main route of electrons operating during oxygenic photosynthesis, called linear electron flow or Z scheme, auxiliary routes of electron transfer in interaction with the main pathway have been described. These reactions which include non-photochemical reduction of intersystem electron carriers, cyclic electron flow around PSI, oxidation by molecular O(2) of the PQ pool or of the PSI electron acceptors, participate in the flexibility of photosynthesis by avoiding over-reduction of electron carriers and modulating the NADPH/ATP ratio depending on the metabolic demand. Forward or reverse genetic approaches performed in model organisms such as Arabidopsis thaliana for higher plants, Chlamydomonas reinhardtii for green algae and Synechocystis for cyanobacteria allowed identifying molecular components involved in these auxiliary electron transport pathways, including Ndh-1, Ndh-2, PGR5, PGRL1, PTOX and flavodiiron proteins. In this article, we discuss the diversity of auxiliary routes of electron transport in microalgae, with particular focus in the presence of these components in the microalgal genomes recently sequenced. We discuss how these auxiliary mechanisms of electron transport may have contributed to the adaptation of microalgal photosynthesis to diverse and changing environments.

  11. Small Substrate Transport and Mechanism of a Molybdate ATP Binding Cassette Transporter in a Lipid Environment*

    PubMed Central

    Rice, Austin J.; Harrison, Alistair; Alvarez, Frances J. D.; Davidson, Amy L.; Pinkett, Heather W.

    2014-01-01

    Embedded in the plasma membrane of all bacteria, ATP binding cassette (ABC) importers facilitate the uptake of several vital nutrients and cofactors. The ABC transporter, MolBC-A, imports molybdate by passing substrate from the binding protein MolA to a membrane-spanning translocation pathway of MolB. To understand the mechanism of transport in the biological membrane as a whole, the effects of the lipid bilayer on transport needed to be addressed. Continuous wave-electron paramagnetic resonance and in vivo molybdate uptake studies were used to test the impact of the lipid environment on the mechanism and function of MolBC-A. Working with the bacterium Haemophilus influenzae, we found that MolBC-A functions as a low affinity molybdate transporter in its native environment. In periods of high extracellular molybdate concentration, H. influenzae makes use of parallel molybdate transport systems (MolBC-A and ModBC-A) to take up a greater amount of molybdate than a strain with ModBC-A alone. In addition, the movement of the translocation pathway in response to nucleotide binding and hydrolysis in a lipid environment is conserved when compared with in-detergent analysis. However, electron paramagnetic resonance spectroscopy indicates that a lipid environment restricts the flexibility of the MolBC translocation pathway. By combining continuous wave-electron paramagnetic resonance spectroscopy and substrate uptake studies, we reveal details of molybdate transport and the logistics of uptake systems that employ multiple transporters for the same substrate, offering insight into the mechanisms of nutrient uptake in bacteria. PMID:24722984

  12. Small substrate transport and mechanism of a molybdate ATP binding cassette transporter in a lipid environment.

    PubMed

    Rice, Austin J; Harrison, Alistair; Alvarez, Frances J D; Davidson, Amy L; Pinkett, Heather W

    2014-05-23

    Embedded in the plasma membrane of all bacteria, ATP binding cassette (ABC) importers facilitate the uptake of several vital nutrients and cofactors. The ABC transporter, MolBC-A, imports molybdate by passing substrate from the binding protein MolA to a membrane-spanning translocation pathway of MolB. To understand the mechanism of transport in the biological membrane as a whole, the effects of the lipid bilayer on transport needed to be addressed. Continuous wave-electron paramagnetic resonance and in vivo molybdate uptake studies were used to test the impact of the lipid environment on the mechanism and function of MolBC-A. Working with the bacterium Haemophilus influenzae, we found that MolBC-A functions as a low affinity molybdate transporter in its native environment. In periods of high extracellular molybdate concentration, H. influenzae makes use of parallel molybdate transport systems (MolBC-A and ModBC-A) to take up a greater amount of molybdate than a strain with ModBC-A alone. In addition, the movement of the translocation pathway in response to nucleotide binding and hydrolysis in a lipid environment is conserved when compared with in-detergent analysis. However, electron paramagnetic resonance spectroscopy indicates that a lipid environment restricts the flexibility of the MolBC translocation pathway. By combining continuous wave-electron paramagnetic resonance spectroscopy and substrate uptake studies, we reveal details of molybdate transport and the logistics of uptake systems that employ multiple transporters for the same substrate, offering insight into the mechanisms of nutrient uptake in bacteria. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  13. Supported Text in Electronic Reading Environments.

    ERIC Educational Resources Information Center

    Horney, Mark A.; Anderson-Inman, Lynne

    1999-01-01

    Defines "electronic books," and shares examples of prior research on the use of such environments to improve the reading fluency and comprehension of students with reading difficulties. Presents a taxonomy of the types of supportive resources that have emerged from efforts to design and research the use of electronic books, and presents…

  14. Electronic transport in patterned graphene nanoroads

    NASA Astrophysics Data System (ADS)

    de Almeida, J. M.; Rocha, A. R.; Singh, Abhshek K.; Fazzio, A.; da Silva, Antônio J. R.

    2013-12-01

    Graphane, hydrogenated graphene, can be patterned into electronic devices by selectively removing hydrogen atoms. The most simple of such devices is the so-called nanoroad, analogous to the graphene nanoribbon, where confinement—and the opening of a gap—is obtained without the need for breaking the carbon bonds. In this work we address the electronic transport properties of such systems considering different hydrogen impurities within the conduction channel. We show, using a combination of density functional theory and non-equilibrium Green’s functions, that hydrogen leads to significant changes in the transport properties and in some cases to current polarization.

  15. Radiation Hardened Electronics for Space Environments (RHESE)

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Adams, James H.; Frazier, Donald O.; Patrick, Marshall C.; Watson, Michael D.; Johnson, Michael A.; Cressler, John D.; Kolawa, Elizabeth A.

    2007-01-01

    Radiation Environmental Modeling is crucial to proper predictive modeling and electronic response to the radiation environment. When compared to on-orbit data, CREME96 has been shown to be inaccurate in predicting the radiation environment. The NEDD bases much of its radiation environment data on CREME96 output. Close coordination and partnership with DoD radiation-hardened efforts will result in leveraged - not duplicated or independently developed - technology capabilities of: a) Radiation-hardened, reconfigurable FPGA-based electronics; and b) High Performance Processors (NOT duplication or independent development).

  16. Electron Transport in Solvated Porous Nanocarbons

    NASA Astrophysics Data System (ADS)

    Baskin, Artem; Kral, Petr

    2013-03-01

    We study electron transport in porous nanocarbons (PNCs) in vacuum, gases, and ionic solutions. Using state of the art electronic structure methods and nonequilibrium Green's functions techniques, we explore the band structures and the current-voltage characteristics of PNCs with different sizes, shapes, positioning and functionalization of pores, edges, and types of electrodes. We find that the presence of ions and molecules around PNCs can largely influence their electron transmissivity. Therefore, PNCs could be used for highly sensitive detection of ions and polar molecules passing around them.

  17. Electron transport property of tetrathiafulvalene molecule

    SciTech Connect

    Mondal, Rajkumar; Bhattacharya, Barnali; Deb, Jyotirmoy; Sarkar, Utpal

    2016-05-23

    We have investigated electron transport behavior of tetrathiafulvalene molecule connected with zigzag graphene nanoribbon (zGNR) using density functional theory combined with non-equilibrium Green’s function method. We have reported the transmission coefficient of the scattering region at different bias voltage to explain the nature of the current.

  18. Numerical solution of the electron transport equation

    NASA Astrophysics Data System (ADS)

    Woods, Mark

    The electron transport equation has been solved many times for a variety of reasons. The main difficulty in its numerical solution is that it is a very stiff boundary value problem. The most common numerical methods for solving boundary value problems are symmetric collocation methods and shooting methods. Both of these types of methods can only be applied to the electron transport equation if the boundary conditions are altered with unrealistic assumptions because they require too many points to be practical. Further, they result in oscillating and negative solutions, which are physically meaningless for the problem at hand. For these reasons, all numerical methods for this problem to date are a bit unusual because they were designed to try and avoid the problem of extreme stiffness. This dissertation shows that there is no need to introduce spurious boundary conditions or invent other numerical methods for the electron transport equation. Rather, there already exists methods for very stiff boundary value problems within the numerical analysis literature. We demonstrate one such method in which the fast and slow modes of the boundary value problem are essentially decoupled. This allows for an upwind finite difference method to be applied to each mode as is appropriate. This greatly reduces the number of points needed in the mesh, and we demonstrate how this eliminates the need to define new boundary conditions. This method is verified by showing that under certain restrictive assumptions, the electron transport equation has an exact solution that can be written as an integral. We show that the solution from the upwind method agrees with the quadrature evaluation of the exact solution. This serves to verify that the upwind method is properly solving the electron transport equation. Further, it is demonstrated that the output of the upwind method can be used to compute auroral light emissions.

  19. Electronic transport in partially ionized water plasmas

    NASA Astrophysics Data System (ADS)

    French, Martin; Redmer, Ronald

    2017-09-01

    We use ab initio simulations based on density functional theory to calculate the electrical and thermal conductivities of electrons in partially ionized water plasmas at densities above 0.1 g/cm3. The resulting conductivity data are then fitted to analytic expressions for convenient application. For low densities, we develop a simple and fully analytic model for electronic transport in low-density plasmas in the chemical picture using the relaxation-time approximation. In doing so, we derive a useful analytic expression for electronic transport cross sections with neutral particles, based on a model potential. In the regime of thermal ionization, electrical conductivities from the analytic model agree with the ab initio data within a factor of 2. Larger deviations are observed for the thermal conductivity, and their origin is discussed. Our results are relevant for modeling the interior and evolution of water-rich planets as well as for technical plasma applications.

  20. Electronic materials processing and the microgravity environment

    NASA Technical Reports Server (NTRS)

    Witt, A. F.

    1988-01-01

    The nature and origin of deficiencies in bulk electronic materials for device fabrication are analyzed. It is found that gravity generated perturbations during their formation account largely for the introduction of critical chemical and crystalline defects and, moreover, are responsible for the still existing gap between theory and experiment and thus for excessive reliance on proprietary empiricism in processing technology. Exploration of the potential of reduced gravity environment for electronic materials processing is found to be not only desirable but mandatory.

  1. Modeling electronic quantum transport with machine learning

    NASA Astrophysics Data System (ADS)

    Lopez-Bezanilla, Alejandro; von Lilienfeld, O. Anatole

    2014-06-01

    We present a machine learning approach to solve electronic quantum transport equations of one-dimensional nanostructures. The transmission coefficients of disordered systems were computed to provide training and test data sets to the machine. The system's representation encodes energetic as well as geometrical information to characterize similarities between disordered configurations, while the Euclidean norm is used as a measure of similarity. Errors for out-of-sample predictions systematically decrease with training set size, enabling the accurate and fast prediction of new transmission coefficients. The remarkable performance of our model to capture the complexity of interference phenomena lends further support to its viability in dealing with transport problems of undulatory nature.

  2. Landauer fields in electron transport and electromigration

    NASA Astrophysics Data System (ADS)

    Sorbello, R. S.

    1998-03-01

    Landauer's classic 1957 paper on electron transport in the presence of localized scatterers has provided a powerful approach for analysing the local transport field and the driving force for electromigration in metals. This approach leads to local fields which are associated with residual resistivity dipoles and with carrier density modulation, and these Landauer fields contribute to the electromigration driving force. The nature of these fields and their role in electromigration are critically examined and comparisons are made with the results of more elaborate quantum-mechanical theories.

  3. The effect of electron-electron interaction induced dephasing on electronic transport in graphene nanoribbons

    SciTech Connect

    Kahnoj, Sina Soleimani; Touski, Shoeib Babaee; Pourfath, Mahdi E-mail: pourfath@iue.tuwien.ac.at

    2014-09-08

    The effect of dephasing induced by electron-electron interaction on electronic transport in graphene nanoribbons is theoretically investigated. In the presence of disorder in graphene nanoribbons, wavefunction of electrons can set up standing waves along the channel and the conductance exponentially decreases with the ribbon's length. Employing the non-equilibrium Green's function formalism along with an accurate model for describing the dephasing induced by electron-electron interaction, we show that this kind of interaction prevents localization and transport of electrons remains in the diffusive regime where the conductance is inversely proportional to the ribbon's length.

  4. Electron ripple injection concept for transport control

    SciTech Connect

    Choe, W.; Ono, M.; Hwang, Y.S.

    1992-01-01

    Recent experiments in many devices have provided firm evidence that the edge radial electric field profile differs between L- and H-modes, and that these fields can greatly modify transport in tokamak plasmas. A nonintrusive method for inducing radial electric field based on electron ripple injection is being developed by the CDX-U group. This technique utilizes a pair of special coils to create a local magnetic field ripple to trap the electrons at the edge of the plasma. The trapped electrons then drift into the plasma due to the [del]B drift. An ECH power is applied to accelerate electrons to sufficient perpendicular energy to penetrate into the plasma. Application of ECH power to the trapped electrons should provide the desired 20 A of electron current with electrons of a few keV of energy and v[perpendicular]/v[parallel] [much gt] 1. A controlled experiment to investigate the physics of ECH aided ripple injection has been designed on CDX-U. With the set of ripple coils designed for CDX-U, a ripple fraction of [delta] ([double bond] [del]B/B[sub av]) [approximately] 5% is attainable. At this ripple fraction, electrons are trapped if v[perpendicular]/v[parallel] [much gt] 1> (2[delta])[sup [minus][1/2

  5. Correlated electrons in a dissipative environment

    NASA Astrophysics Data System (ADS)

    Bulla, R.

    2009-12-01

    When a system of correlated electrons is embedded in a dissipative environment, new emergent phenomena might occur due to the interplay of correlation and dissipation. Here we focus on quantum impurity systems with coupling to a bosonic bath. For the theoretical investigation we introduce the bosonic numerical renormalization group method which has been initially set up for the spin-boson model. The role of both correlations and dissipation is described in the context of two-electron transfer systems. We also discuss prospects for the investigation of lattice models of correlated electrons with coupling to a dissipative bath.

  6. Self-consistent electron transport in tokamaks

    SciTech Connect

    Gatto, R.; Chavdarovski, I.

    2007-09-15

    Electron particle, momentum, and energy fluxes in axisymmetric toroidal devices are derived from a version of the action-angle collision operator that includes both diffusion and drag in action-space [D. A. Hitchcock, R. D. Hazeltine, and S. M. Mahajan, Phys. Fluids 26, 2603 (1983); H. E. Mynick, J. Plasma Phys. 39, 303 (1988)]. A general result of the theory is that any contribution to transport originating directly from the toroidal frequency of the particle motion is constrained to be zero when the electron temperature is equal to the ion temperature. In particular, this constraint applies to those components of the particle and energy fluxes that are proportional to the magnetic shear, independent of the underlying turbulence and of whether the particles are trapped or untrapped. All the total fluxes describing collisionless transport of passing electrons in steady-state magnetic turbulence contain contributions proportional to the conventional thermodynamic drives, which are always outward, and contributions proportional to the magnetic shear, which have both magnitude and sign dependent on the ion-electron temperature ratio. The turbulent generalization of Ohm's law includes a hyper-resistive term, which flattens the current density profile on a fast time scale, and a turbulent electric field, which can have both signs depending on the electron-ion temperature ratio.

  7. Low energy electron transport in furfural

    NASA Astrophysics Data System (ADS)

    Lozano, Ana I.; Krupa, Kateryna; Ferreira da Silva, Filipe; Limão-Vieira, Paulo; Blanco, Francisco; Muñoz, Antonio; Jones, Darryl B.; Brunger, Michael J.; García, Gustavo

    2017-09-01

    We report on an initial investigation into the transport of electrons through a gas cell containing 1 mTorr of gaseous furfural. Results from our Monte Carlo simulation are implicitly checked against those from a corresponding electron transmission measurement. To enable this simulation a self-consistent cross section data base was constructed. This data base is benchmarked through new total cross section measurements which are also described here. In addition, again to facilitate the simulation, our preferred energy loss distribution function is presented and discussed.

  8. Extracellular Electron Transport (EET): Metal Cycling in Extreme Places

    NASA Astrophysics Data System (ADS)

    Nealson, K. H.

    2014-12-01

    Extracellular electron transport, or EET, is the process whereby bacteria either donate electrons to an electron acceptor (usually insoluble), or take up electrons from and electron donor (usually insoluble) that is located outside the cell. Iron cycling is inherently linked to EET, as both reduced iron (electron donors), and oxidized iron (electron acceptors) can be found as insoluble minerals, and require specialized molecular machines to accomplish these extracellular geobiological reactions. Bacteria in the group Shewanella are able to catalyze EET in both directions, and are involved with a number of different iron conversions, but are not good role models for extreme conditions - to our knowledge there are no shewanellae that are tolerant to extremes of temperature or pH, the two usual. This being said, when cells are energy starved via limitation for electron acceptors, they respond by turning on the system(s) for EET. Thus, in this presentation the known mechanism(s) of EET will be discussed, along with recent findings and reports of EET-capable organisms from a variety of extreme environments. From these data, I put forward the hypothesis that there are many microbes (many of them from extreme environments) that will be resistant to cultivation by "standard microbiological methods", yet lend themselves well to cultivation via electrochemical methods.

  9. Censorship, the Classroom, and the Electronic Environment.

    ERIC Educational Resources Information Center

    Considine, David M.

    1985-01-01

    Suggests that the notion that the young can be protected by denying them access to materials has been invalidated by the expansion of the electronic environment and changes in community standards. Argues that since students today cannot avoid exposure to questionable material, it is important to see that the exposure they receive is educated and…

  10. Public Service Guidelines in an Electronic Environment.

    ERIC Educational Resources Information Center

    Barkley, Daniel C.

    1998-01-01

    In today's electronic environment, government information librarians face new challenges, especially in the arena of quality public-service provision. Given the lack of clear guidelines that Federal Depository Library Program participants follow, and based upon suggested guidelines of reference-oriented literature, a new set of public services…

  11. Electron transport in pure and doped hematite.

    PubMed

    Liao, Peilin; Toroker, Maytal Caspary; Carter, Emily A

    2011-04-13

    Hematite (α-Fe(2)O(3)) is a promising candidate for photoelectrochemical splitting of water. However, its intrinsically poor conductivity is a major drawback. Doping hematite to make it either p-type or n-type enhances its measured conductivity. We use quantum mechanics to understand how titanium, zirconium, silicon, or germanium n-type doping affects the electron transport mechanism in hematite. Our results suggest that zirconium, silicon, or germanium doping is superior to titanium doping because the former dopants do not act as electron trapping sites due to the higher instability of Zr(III) compared to Ti(III) and the more covalent interactions between silicon (germanium) and oxygen. This suggests that use of n-type dopants that easily ionize completely or promote covalent bonds to oxygen can provide more charge carriers while not inhibiting transport.

  12. Electronic transport in methylated fragments of DNA

    SciTech Connect

    Almeida, M. L. de; Oliveira, J. I. N.; Lima Neto, J. X.; Gomes, C. E. M.; Fulco, U. L. Albuquerque, E. L.; Freire, V. N.; Caetano, E. W. S.; Moura, F. A. B. F. de; Lyra, M. L.

    2015-11-16

    We investigate the electronic transport properties of methylated deoxyribonucleic-acid (DNA) strands, a biological system in which methyl groups are added to DNA (a major epigenetic modification in gene expression), sandwiched between two metallic platinum electrodes. Our theoretical simulations apply an effective Hamiltonian based on a tight-binding model to obtain current-voltage curves related to the non-methylated/methylated DNA strands. The results suggest potential applications in the development of novel biosensors for molecular diagnostics.

  13. Electronic transport in arrays of gold nanocrystals

    NASA Astrophysics Data System (ADS)

    Parthasarathy, Raghuveer

    We examine electronic transport through two-dimensional arrays of gold nanocrystals. Recently developed techniques of particle synthesis and array self-assembly provide ordered (and disordered) monolayers of six-nanometer diameter gold nanocrystals on substrates with in-plane electrodes. These well-characterized superlattices allow investigation of basic questions about electronic conduction in metal quantum dot assemblies, answers to which have previously remained elusive. We first address the relation between current and voltage. Central to transport is the Coulomb blockade, the energetic cost of adding a single electron to a nanocrystal. Theoretical studies suggest power-law scaling of current beyond a threshold voltage in Coulomb blockade dominated systems. In ordered arrays, our data follow a power-law form, but with a scaling exponent significantly higher than the theoretical prediction. In disordered arrays, power-law scaling is violated; we explain that disorder disturbs the branching of current-carrying paths responsible for power-law conduction. Second, we examine the effect of temperature on transport. We find a large low-temperature regime (up to about 100 K) in which thermal energy acts only to linearly suppress the threshold voltage, leaving the current scale unaffected. We provide a simple, analytic model of thermally assisted tunneling which quantitatively describes the data. Third, we develop a simple and novel technique to tune the interparticle electronic couplings of the arrays---deposition of small amounts of germanium on the monolayers. The germanium dopant lowers the voltage threshold, and also increases conductivity. It also increases the temperature dependence of transport, suggesting the introduction of trapped states between the gold nanocrystal cores.

  14. Electron transport fluxes in potato plateau regime

    SciTech Connect

    Shaing, K.C.; Hazeltine, R.D.

    1997-12-01

    Electron transport fluxes in the potato plateau regime are calculated from the solutions of the drift kinetic equation and fluid equations. It is found that the bootstrap current density remains finite in the region close to the magnetic axis, although it decreases with increasing collision frequency. This finite amount of the bootstrap current in the relatively collisional regime is important in modeling tokamak startup with 100{percent} bootstrap current. {copyright} {ital 1997 American Institute of Physics.}

  15. Electronic transport in methylated fragments of DNA

    NASA Astrophysics Data System (ADS)

    de Almeida, M. L.; Oliveira, J. I. N.; Lima Neto, J. X.; Gomes, C. E. M.; Fulco, U. L.; Albuquerque, E. L.; Freire, V. N.; Caetano, E. W. S.; de Moura, F. A. B. F.; Lyra, M. L.

    2015-11-01

    We investigate the electronic transport properties of methylated deoxyribonucleic-acid (DNA) strands, a biological system in which methyl groups are added to DNA (a major epigenetic modification in gene expression), sandwiched between two metallic platinum electrodes. Our theoretical simulations apply an effective Hamiltonian based on a tight-binding model to obtain current-voltage curves related to the non-methylated/methylated DNA strands. The results suggest potential applications in the development of novel biosensors for molecular diagnostics.

  16. Electronic transport in smectic liquid crystals

    NASA Astrophysics Data System (ADS)

    Shiyanovskaya, I.; Singer, K. D.; Twieg, R. J.; Sukhomlinova, L.; Gettwert, V.

    2002-04-01

    Time-of-flight measurements of transient photoconductivity have revealed bipolar electronic transport in phenylnaphthalene and biphenyl liquid crystals (LC), which exhibit several smectic mesophases. In the phenylnaphthalene LC, the hole mobility is significantly higher than the electron mobility and exhibits different temperature and phase behavior. Electron mobility in the range ~10-5 cm2/V s is temperature activated and remains continuous at the phase transitions. However, hole mobility is nearly temperature independent within the smectic phases, but is very sensitive to smectic order, 10-3 cm2/V s in the smectic-B (Sm-B) and 10-4 cm2/V s in the smectic-A (Sm-A) mesophases. The different behavior for holes and electron transport is due to differing transport mechanisms. The electron mobility is apparently controlled by rate-limiting multiple shallow trapping by impurities, but hole mobility is not. To explain the lack of temperature dependence for hole mobility within the smectic phases we consider two possible polaron transport mechanisms. The first mechanism is based on the hopping of Holstein small polarons in the nonadiabatic limit. The polaron binding energy and transfer integral values, obtained from the model fit, turned out to be sensitive to the molecular order in smectic mesophases. A second possible scenario for temperature-independent hole mobility involves the competion between two different polaron mechanisms involving so-called nearly small molecular polarons and small lattice polarons. Although the extracted transfer integrals and binding energies are reasonable and consistent with the model assumptions, the limited temperature range of the various phases makes it difficult to distinguish between any of the models. In the biphenyl LCs both electron and hole mobilities exhibit temperature activated behavior in the range of 10-5 cm2/V s without sensitivity to the molecular order. The dominating transport mechanism is considered as multiple trapping

  17. Runaway electron transport via tokamak microturbulence

    SciTech Connect

    Hauff, T.; Jenko, F.

    2009-10-15

    The mechanisms found for the magnetic transport of fast ions in the work of Hauff et al. [Phys. Rev. Lett. 102, 075004 (2009)] are extended to the diffusion of runaway electrons. Due to their smaller mass and larger energy, they behave strongly relativistically, for which reason the scaling laws defined previously have to be modified. It is found that due to these changes, the regime of constant magnetic transport does not exist anymore, but diffusivity scales with E{sup -1} for magnetic transport, or even with E{sup -2} in the case that finite gyroradius effects become important. It is shown that the modified analytical approaches are able to explain the surprisingly small values found in experiments, although it cannot be excluded that possibly other reduction mechanisms are present at the same time.

  18. Electron ripple injection concept for transport control

    SciTech Connect

    Choe, W.; Ono, M.; Hwang, Y.S.

    1992-10-01

    Recent experiments in many devices have provided firm evidence that the edge radial electric field profile differs between L- and H-modes, and that these fields can greatly modify transport in tokamak plasmas. A nonintrusive method for inducing radial electric field based on electron ripple injection is being developed by the CDX-U group. This technique utilizes a pair of special coils to create a local magnetic field ripple to trap the electrons at the edge of the plasma. The trapped electrons then drift into the plasma due to the {del}B drift. An ECH power is applied to accelerate electrons to sufficient perpendicular energy to penetrate into the plasma. Application of ECH power to the trapped electrons should provide the desired 20 A of electron current with electrons of a few keV of energy and v{perpendicular}/v{parallel} {much_gt} 1. A controlled experiment to investigate the physics of ECH aided ripple injection has been designed on CDX-U. With the set of ripple coils designed for CDX-U, a ripple fraction of {delta} ({double_bond} {del}B/B{sub av}) {approximately} 5% is attainable. At this ripple fraction, electrons are trapped if v{perpendicular}/v{parallel} {much_gt} 1> (2{delta}){sup {minus}{1/2}} {approx}3. A resonant cavity box was fabricated for efficient heating of the trapped electrons. It is also capable of measuring the effect of the field ripple in conjunction with trapped electrons. Some preliminary results are given.

  19. Electronic transport properties in graphene oxide frameworks

    NASA Astrophysics Data System (ADS)

    Zhu, P.; Cruz-Silva, E.; Meunier, V.

    2014-02-01

    The electronic transport properties in multiterminal graphene oxide framework (GOF) materials are investigated using a combination of theoretical and computational methods. GOFs make up four-terminal [origin=c]90H-shaped GNR-L-GNR junctions where sandwiched boronic acid molecules (L) are covalently linked to two graphene nanoribbons (GNRs) of different edge chiralities. The transport properties are governed by both tunneling and quasiresonant regimes. We determine how the presence of linker molecules affects the transport properties and establish that the through-molecule transport properties can be tuned by varying the chemical composition of the pillar molecules but are not significantly modified when changing the type of electrodes from zigzag GNRs to armchair GNRs. In addition, we find that in multilinker systems containing two parallel molecules in the device area, the coupling between the molecules can lead to both constructive and destructive quantum interferences. We also examine the inability of the classical Kirchhoff's superposition law to account for electron flow in multilinker GOF nanonetworks.

  20. Quantum electron transport in toroidal carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Jack, Mark; Encinosa, Mario

    2008-03-01

    Electron transport under bias is treated in tight-binding approximation using a non-equilibrium Green's function approach. Density-of-states D(E), transmissivity T(E), and current ISD are calculated through a (3,3) armchair nanotorus with laterally attached metallic leads and a magnetic field penetrating the toroidal plane. Plateaus in T(E) through the torus are observed as a function of both the relative angle between leads and magnetic flux. Initial computational studies performed with 1800 atoms and attached leads show substantial computational slowdown when increasing the system size by a factor of two. Results are generated by inverting the device Hamiltonian with a standard recursion method extended to account for unit cell toroidal closure. Significant computational speed-up is expected for a parallelized code on a multiprocessor computer cluster. The dependence of electronic features on torus size and torus curvature is tested for three tori with 900, 1800 and 3600 carbon atoms, respectively. References: 1. M. Jack and M. Encinosa, Quantum electron transport in toroidal carbon nanotubes with metallic leads. ArXiv: quant-ph/0709.0760. 2. M. Encinosa and M. Jack, Dipole and solenoidal magnetic moments of electronic surface currents on toroidal nanostructures. J. Comp.-Aided Mat. Design (Springer), 14 (1) (2007) 65 -- 71.

  1. Studies of runaway electron transport in TEXT

    SciTech Connect

    Wang, Pei-Wen.

    1991-12-01

    The transport of runaway electrons is studied by a plasma position shift experiment and by imposing an externally applied perturbing magnetic field on the edge. The perturbing magnetic field can produce either magnetic islands or, with overlapping islands, a stochastic field. Hard X-ray signals are then measured and compared with analytic and numerical model results. Diffusion coefficients in the edge, {approximately}10{sup 4} cm{sup 2}/sec, and inside the plasma, {approximately}10{sup 2} {minus} 10{sup 3} cm{sup 2}/sec, are estimated. The averaged drift effects are small and the intrinsic magnetic fluctuations are estimated to be < (b{sub r}/B{sub 0}){sup 2} > {approximately}1-{sup {minus}10} at the edge and decreasing inward. Runaway electrons are a good diagnostic of the magnetic fluctuations. It is considered that the magnetic fluctuations have a negligible effect on electron thermal diffusion in the edge plasma.

  2. On electron transport through Geobacter biofilms.

    PubMed

    Bond, Daniel R; Strycharz-Glaven, Sarah M; Tender, Leonard M; Torres, César I

    2012-06-01

    Geobacter spp. can form a biofilm that is more than 20 μm thick on an anode surface by utilizing the anode as a terminal respiratory electron acceptor. Just how microbes transport electrons through a thick biofilm and across the biofilm/anode interface, and what determines the upper limit to biofilm thickness and catalytic activity (i.e., current, the rate at which electrons are transferred to the anode), are fundamental questions attracting substantial attention. A significant body of experimental evidence suggests that electrons are transferred from individual cells through a network of cytochromes associated with cell outer membranes, within extracellular polymeric substances, and along pili. Here, we describe what is known about this extracellular electron transfer process, referred to as electron superexchange, and its proposed role in biofilm anode respiration. Superexchange is able to account for many different types of experimental results, as well as for the upper limit to biofilm thickness and catalytic activity that Geobacter biofilm anodes can achieve.

  3. Electronic transport in graphene-based heterostructures

    SciTech Connect

    Tan, J. Y.; Avsar, A.; Balakrishnan, J.; Taychatanapat, T.; O'Farrell, E. C. T.; Eda, G.; Castro Neto, A. H.; Koon, G. K. W.; Özyilmaz, B.; Watanabe, K.; Taniguchi, T.

    2014-05-05

    While boron nitride (BN) substrates have been utilized to achieve high electronic mobilities in graphene field effect transistors, it is unclear how other layered two dimensional (2D) crystals influence the electronic performance of graphene. In this Letter, we study the surface morphology of 2D BN, gallium selenide (GaSe), and transition metal dichalcogenides (tungsten disulfide (WS{sub 2}) and molybdenum disulfide (MoS{sub 2})) crystals and their influence on graphene's electronic quality. Atomic force microscopy analysis shows that these crystals have improved surface roughness (root mean square value of only ∼0.1 nm) compared to conventional SiO{sub 2} substrate. While our results confirm that graphene devices exhibit very high electronic mobility (μ) on BN substrates, graphene devices on WS{sub 2} substrates (G/WS{sub 2}) are equally promising for high quality electronic transport (μ ∼ 38 000 cm{sup 2}/V s at room temperature), followed by G/MoS{sub 2} (μ ∼ 10 000 cm{sup 2}/V s) and G/GaSe (μ ∼ 2200 cm{sup 2}/V s). However, we observe a significant asymmetry in electron and hole conduction in G/WS{sub 2} and G/MoS{sub 2} heterostructures, most likely due to the presence of sulphur vacancies in the substrate crystals. GaSe crystals are observed to degrade over time even under ambient conditions, leading to a large hysteresis in graphene transport making it a less suitable substrate.

  4. Alternative electron transport pathways in photosynthesis: a confluence of regulation.

    PubMed

    Alric, Jean; Johnson, Xenie

    2017-06-01

    Photosynthetic reactions proceed along a linear electron transfer chain linking water oxidation at photosystem II (PSII) to CO2 reduction in the Calvin-Benson-Bassham cycle. Alternative pathways poise the electron carriers along the chain in response to changing light, temperature and CO2 inputs, under prolonged hydration stress and during development. We describe recent literature that reports the physiological functions of new molecular players. Such highlights include the flavodiiron proteins and their important role in the green lineage. The parsing of the proton-motive force between ΔpH and Δψ, regulated in many different ways (cyclic electron flow, ATPsynthase conductivity, ion/H(+) transporters), is comprehensively reported. This review focuses on an integrated description of alternative electron transfer pathways and how they contribute to photosynthetic productivity in the context of plant fitness to the environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Radiation Hardened Electronics for Extreme Environments

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Watson, Michael D.

    2007-01-01

    The Radiation Hardened Electronics for Space Environments (RHESE) project consists of a series of tasks designed to develop and mature a broad spectrum of radiation hardened and low temperature electronics technologies. Three approaches are being taken to address radiation hardening: improved material hardness, design techniques to improve radiation tolerance, and software methods to improve radiation tolerance. Within these approaches various technology products are being addressed including Field Programmable Gate Arrays (FPGA), Field Programmable Analog Arrays (FPAA), MEMS Serial Processors, Reconfigurable Processors, and Parallel Processors. In addition to radiation hardening, low temperature extremes are addressed with a focus on material and design approaches.

  6. Hetero-Interfaces for Extreme Electronic Environments

    DTIC Science & Technology

    2014-07-23

    ELECTRONIC ENVIRONMENTS Quasi-two-dimensional electron gas (Q-2D-EG) forms at the interface between two perovskite band insulators; LaAlO3 (LAO) and...BO2 stacking in perovskite phase (Fig. 1) [2]. For example, a SrTiO3/LaAlO3 interface normal to > produces a charge- balanced layer of SrTiO3...pointing out that interfacial strain in a perovskite heterostructure has been shown to alter its physical properties. For example, thin film STO can exhibit

  7. Logistics, electronic commerce, and the environment

    NASA Astrophysics Data System (ADS)

    Sarkis, Joseph; Meade, Laura; Talluri, Srinivas

    2002-02-01

    Organizations realize that a strong supporting logistics or electronic logistics (e-logistics) function is important from both commercial and consumer perspectives. The implications of e-logistics models and practices cover the forward and reverse logistics functions of organizations. They also have direct and profound impact on the natural environment. This paper will focus on a discussion of forward and reverse e-logistics and their relationship to the natural environment. After discussion of the many pertinent issues in these areas, directions of practice and implications for study and research are then described.

  8. The AE-8 trapped electron model environment

    NASA Technical Reports Server (NTRS)

    Vette, James I.

    1991-01-01

    The machine sensible version of the AE-8 electron model environment was completed in December 1983. It has been sent to users on the model environment distribution list and is made available to new users by the National Space Science Data Center (NSSDC). AE-8 is the last in a series of terrestrial trapped radiation models that includes eight proton and eight electron versions. With the exception of AE-8, all these models were documented in formal reports as well as being available in a machine sensible form. The purpose of this report is to complete the documentation, finally, for AE-8 so that users can understand its construction and see the comparison of the model with the new data used, as well as with the AE-4 model.

  9. Distribution of tunnelling times for quantum electron transport

    NASA Astrophysics Data System (ADS)

    Rudge, Samuel L.; Kosov, Daniel S.

    2016-03-01

    In electron transport, the tunnelling time is the time taken for an electron to tunnel out of a system after it has tunnelled in. We define the tunnelling time distribution for quantum processes in a dissipative environment and develop a practical approach for calculating it, where the environment is described by the general Markovian master equation. We illustrate the theory by using the rate equation to compute the tunnelling time distribution for electron transport through a molecular junction. The tunnelling time distribution is exponential, which indicates that Markovian quantum tunnelling is a Poissonian statistical process. The tunnelling time distribution is used not only to study the quantum statistics of tunnelling along the average electric current but also to analyse extreme quantum events where an electron jumps against the applied voltage bias. The average tunnelling time shows distinctly different temperature dependence for p- and n-type molecular junctions and therefore provides a sensitive tool to probe the alignment of molecular orbitals relative to the electrode Fermi energy.

  10. Modeling Electronic Quantum Transport with Machine Learning

    DOE PAGES

    Lopez Bezanilla, Alejandro; von Lilienfeld Toal, Otto A.

    2014-06-11

    We present a machine learning approach to solve electronic quantum transport equations of one-dimensional nanostructures. The transmission coefficients of disordered systems were computed to provide training and test data sets to the machine. The system’s representation encodes energetic as well as geometrical information to characterize similarities between disordered configurations, while the Euclidean norm is used as a measure of similarity. Errors for out-of-sample predictions systematically decrease with training set size, enabling the accurate and fast prediction of new transmission coefficients. The remarkable performance of our model to capture the complexity of interference phenomena lends further support to its viability inmore » dealing with transport problems of undulatory nature.« less

  11. Unconventional dc Transport in Rashba Electron Gases.

    PubMed

    Brosco, Valentina; Benfatto, Lara; Cappelluti, Emmanuele; Grimaldi, Claudio

    2016-04-22

    We discuss the transport properties of a disordered two-dimensional electron gas with strong Rashba spin-orbit coupling. We show that in the high-density regime where the Fermi energy overcomes the energy associated with spin-orbit coupling, dc transport is accurately described by a standard Drude's law, due to a nontrivial compensation between the suppression of backscattering and the relativistic correction to the quasiparticle velocity. On the contrary, when the system enters the opposite dominant spin-orbit regime, Drude's paradigm breaks down and the dc conductivity becomes strongly sensitive to the spin-orbit coupling strength, providing a suitable tool to test the entanglement between spin and charge degrees of freedom in these systems.

  12. Modeling Electronic Quantum Transport with Machine Learning

    SciTech Connect

    Lopez Bezanilla, Alejandro; von Lilienfeld Toal, Otto A.

    2014-06-11

    We present a machine learning approach to solve electronic quantum transport equations of one-dimensional nanostructures. The transmission coefficients of disordered systems were computed to provide training and test data sets to the machine. The system’s representation encodes energetic as well as geometrical information to characterize similarities between disordered configurations, while the Euclidean norm is used as a measure of similarity. Errors for out-of-sample predictions systematically decrease with training set size, enabling the accurate and fast prediction of new transmission coefficients. The remarkable performance of our model to capture the complexity of interference phenomena lends further support to its viability in dealing with transport problems of undulatory nature.

  13. Dissipative electronic transport through double quantum dots irradiated with microwaves

    NASA Astrophysics Data System (ADS)

    Brandes, Tobias; Aguado, Ramon; Platero, Gloria

    2003-03-01

    Double quantum dots in the strong Coulomb blockade regime are realizations of two-level systems defined from two tunnel--splitted ground states, which are separated by a large energy gap from the remaining many--particle states. The interactions between electrons and bosonic degrees of freedom (photons, phonons) in these systems can be tested and manipulated in electronic transport experiments [1]. Monochromatic classical radiation (AC fields, microwaves) gives rise to various non-linear effects such as photo-sidebands or dynamical localization (coherent supression of tunneling) that show up in the time-averaged, stationary electronic current [2]. On the other hand, quantum noise of a dissipative environment strongly influences the transport properties of coupled quantum dots [3,4]. In this contribution, we quantitatively investigate the combined influence of a classical, monochromatic time-dependent AC field and a dissipative boson environment on the non-linear transport through a double quantum dot. We develop a Floquet-like theory [5] that takes into account the effect of the electron reservoirs (leads) and can be numerically evaluated for arbitrary strong AC fields and arbitrary boson environment. In limiting cases we reproduce previous analytical results (polaron tunneling, Tien-Gordon formula). [1] T. Fujisawa, T. H. Oosterkamp, W. G. van der Wiel, B. W. Broer, R. Aguado, S. Tarucha, and L. P. Kouwenhoven, Science 282, 932 (1998); R. H. Blick, D. Pfannkuche, R. J. Haug, K. v. Klitzing, and K. Eberl, Phys. Rev. Lett. 80, 4032 (1998). [2] T. H. Stoof, Yu. V. Nazarov, Phys. Rev. B 53, 1050 (1996). [3] T. Brandes, B. Kramer, Phys. Rev. Lett. 83, 3021 (1999); T. Brandes, F. Renzoni, R. H. Blick, Phys. Rev. B 64, 035319 (2001); T. Brandes, T. Vorrath, Phys. Rev. B 66, 075341 (2002). [4] R. Aguado and L. P. Kouwenhoven, Phys. Rev. Lett, 84, 1986 (2000). [5] M. Grifoni, P. Hänggi, Phys. Rep. 304, 229 (1998).

  14. An environment-dependent semi-empirical tight binding model suitable for electron transport in bulk metals, metal alloys, metallic interfaces, and metallic nanostructures. II. Application—Effect of quantum confinement and homogeneous strain on Cu conductance

    SciTech Connect

    Hegde, Ganesh Povolotskyi, Michael; Kubis, Tillmann; Charles, James; Klimeck, Gerhard

    2014-03-28

    The Semi-Empirical tight binding model developed in Part I Hegde et al. [J. Appl. Phys. 115, 123703 (2014)] is applied to metal transport problems of current relevance in Part II. A systematic study of the effect of quantum confinement, transport orientation, and homogeneous strain on electronic transport properties of Cu is carried out. It is found that quantum confinement from bulk to nanowire boundary conditions leads to significant anisotropy in conductance of Cu along different transport orientations. Compressive homogeneous strain is found to reduce resistivity by increasing the density of conducting modes in Cu. The [110] transport orientation in Cu nanowires is found to be the most favorable for mitigating conductivity degradation since it shows least reduction in conductance with confinement and responds most favorably to compressive strain.

  15. Electronic transport in Pd nanocluster devices

    NASA Astrophysics Data System (ADS)

    Ayesh, A. I.

    2011-03-01

    Palladium nanoclusters with an average diameter of 6.7 nm are prepared by magnetron sputtering and inert gas condensation technique. The nanoclusters are deposited between a pair of electrodes defined by optical lithography to create the device. The electronic transport in the devices is investigated by systematic current-voltage measurements. It is demonstrated through fitting the conductance-temperature profile into a conductance model that the conductance in the device is dominated by tunneling. The fitting provides meaningful physical parameters such as the number of nanoclusters within the conduction path, and it shows that some of the nanoclusters are fused together.

  16. A deterministic electrons and protons transport suite for the study of the Jovian system

    NASA Astrophysics Data System (ADS)

    Badavi, Francis; Nealy, John; Norman, Ryan

    Langley Research Center (LaRC) developed deterministic suite of transport codes for describing the transport of electrons, photons and protons in condensed media is used to simulate the effects and exposures from spectral distributions typical of electrons and protons trapped in planetary magnetic fields. The suite is made of a coupled electrons/ photons deterministic transport procedure (CEPTRN) and a light/heavy ions deterministic transport procedure (HZETRN). The primary purpose for the development of the transport suite is to provide a means for rapidly forming numerous repetitive calculations essential for electrons/protons radiation exposure assessments of complex space structures. Several favorable comparisons have been made with statistically oriented Monte Carlo calculations for typical space environment spectra which have indicated that the transport accuracy has not been compromised at the expense of computational speed. For this presentation the radiation environments of the Galilean satellites Io, Europa, Ganymede and Callisto are used as representative boundary conditions to show the capabilities of the transport suite. The Jovian radiation environment is simulated using the Jet Propulsion Lab. (JPL) GIRE model of 2003. For a limited number of candidate shielding materials, the GIRE produced electrons/protons environments are used as boundary condition to the CEPTRN and HZETRN transport suite to evaluate the particle flux and dose due to electrons and protons at various distances from the planet as a function of latitude, longitude, and altitude.

  17. Electron transport in doped fullerene molecular junctions

    NASA Astrophysics Data System (ADS)

    Kaur, Milanpreet; Sawhney, Ravinder Singh; Engles, Derick

    The effect of doping on the electron transport of molecular junctions is analyzed in this paper. The doped fullerene molecules are stringed to two semi-infinite gold electrodes and analyzed at equilibrium and nonequilibrium conditions of these device configurations. The contemplation is done using nonequilibrium Green’s function (NEGF)-density functional theory (DFT) to evaluate its density of states (DOS), transmission coefficient, molecular orbitals, electron density, charge transfer, current, and conductance. We conclude from the elucidated results that Au-C16Li4-Au and Au-C16Ne4-Au devices behave as an ordinary p-n junction diode and a Zener diode, respectively. Moreover, these doped fullerene molecules do not lose their metallic nature when sandwiched between the pair of gold electrodes.

  18. RHIC electron lens beam transport system design considerations

    SciTech Connect

    Luo, Y.; Heimerle, M.; Fischer, W.; Pikin, A.; Beebe, E.; Bruno, D.; Gassner, D.; Gu, X.; Gupta, R. C.; Hock, J.; Jain, A.; Lambiase, R.; Mapes, M.; Meng, W.; Montag, C.; Oerter, B.; Okamura, M.; Raparia, D.; Tan, Y.; Than, R.; Tuozzolo, J.; Zhang, W.

    2010-08-03

    To apply head-on beam-beam compensation for RHIC, two electron lenses are designed and will be installed at IP6 and IP8. Each electron lens has several sub-systems, including electron gun, electron collector, superconducting main solenoid (SM), diagnostics system and power supply system. In addition to these systems, beam transport system which can transport electron beam from electron gun side to collector side is also needed.

  19. Isolation systems for electronic black-box transportation to orbit

    NASA Astrophysics Data System (ADS)

    Jedrich, Nicholas M.; Pendleton, Scott C.

    1998-06-01

    Servicing the Hubble Space Telescope (HST) requires the safe transportation of electronic Orbital Replacement Units (ORUs) on the Space Transportation System (STS) to replace or enhance the capability of existing units. The delicate design of these electronic ORUs makes it imperative to provide isolation from the STS launch random vibration, while maintaining fundamental modes above the transient load environment. Two methods were developed and used exclusively, on Servicing Mission 2 (SM2), to isolate the ORUs from the environmental launch loads imposed by the STS. The first load isolation system utilizes a refined open/closed cell foam design to provide the required damping and corner frequency, while the second method uses an innovative Viscoelastic Material (VEM) design. This paper addresses both systems as initially designed including finite element (FE) model analysis of the VEM system. Vibration testing of prototype systems and modifications to the design resulting from test will be discussed. The final design as flown on HST SM2 with recommendations for future applications of these technologies in transporting electronic black boxes to orbit will conclude the paper.

  20. Electron Transport through Porphyrin Molecular Junctions

    NASA Astrophysics Data System (ADS)

    Zhou, Qi

    The goal of this work is to study the properties that would affect the electron transport through a porphyrin molecular junction. This work contributes to the field of electron transport in molecular junctions in the following 3 aspects. First of all, by carrying out experiments comparing the conductance of the iron (III) porphyrin (protected) and the free base porphyrin (protected), it is confirmed that the molecular energy level broadening and shifting occurs for porphyrin molecules when coupled with the metal electrodes, and this level broadening and shifting plays an important role in the electron transport through molecular junctions. Secondly, by carrying out an in-situ deprotection of the acetyl-protected free base porphyrin molecules, it is found out that the presence of acetyl groups reduces the conductance. Thirdly, by incorporating the Matrix-assisted laser desorption/ionization (MALDI) spectrum and the in-situ deprotection prior to formation of molecular junctions, it allows a more precise understanding of the molecules involved in the formation of molecular junctions, and therefore allows an accurate analysis of the conductance histogram. The molecules are prepared by self-assembly and the junctions are formed using a Scanning Tunneling Microscopy (STM) molecular break junction technique. The porphyrin molecules are characterized by MALDI in solution before self-assembly to a gold/mica substrate. The self-assembled monolayers (SAMs) of porphyrins on gold are characterized by Ultraviolet-visible (UV-Vis) reflection spectroscopy to confirm that the molecules are attached to the substrate. The SAMs are then characterized by Angle-Resolved X-ray photoelectron spectroscopy (ARXPS) to determine the thickness and the average molecular orientation of the molecular layer. The electron transport is measured by conductance-displacement (G-S) experiments under a given bias (-0.4V). The conductance value of a single molecule is identified by a statistical analysis

  1. Magnetospheric models for electron acceleration and transport in the heliosphere

    NASA Technical Reports Server (NTRS)

    Cooper, J. F.; Baker, D. N.

    1993-01-01

    Electron transport and acceleration processes in the earth's magnetosphere have correspondences to analogous processes affecting electrons in the solar magnetosphere (i.e., heliosphere). Energetic electrons in planetary magnetospheres and the heliosphere are test particles probing transport and acceleration dynamics with minimal effects on dominant magnetic field configurations. Parallels are discussed relating to electron entry into the magnetospheres from interplanetary and interstellar space, circulatory transport processes, and acceleration by electric fields in boundary regions including shocks and magnetotails.

  2. Reconfiguration of Analog Electronics for Extreme Environments

    NASA Technical Reports Server (NTRS)

    Stoica, Adrian; Zebulum, Ricardo; Keymeulen, Didier; Guo, Xin

    2005-01-01

    This paper argues in favor of adaptive reconfiguration as a technique to expand the operational envelope of analog electronics for extreme environments (EE). On a reconfigurable device, although component parameters change in EE, as long as devices still operate, albeit degraded, a new circuit design, suitable for new parameter values, may be mapped into the reconfigurable structure to recover the initial circuit function. Laboratory demonstrations of this technique were performed by JPL in several independent experiments in which bulk CMOS reconfgurable devices were exposed to, and degraded by, high temperatures (approx.300 C) or radiation (300kRad TID), and then recovered by adaptive reconfiguration using evolutionary search algorithms.

  3. Ion age transport: developing devices beyond electronics

    NASA Astrophysics Data System (ADS)

    Demming, Anna

    2014-03-01

    There is more to current devices than conventional electronics. Increasingly research into the controlled movement of ions and molecules is enabling a range of new technologies. For example, as Weihua Guan, Sylvia Xin Li and Mark Reed at Yale University explain, 'It offers a unique opportunity to integrate wet ionics with dry electronics seamlessly'. In this issue they provide an overview of voltage-gated ion and molecule transport in engineered nanochannels. They cover the theory governing these systems and fabrication techniques, as well as applications, including biological and chemical analysis, and energy conversion [1]. Studying the movement of particles in nanochannels is not new. The transport of materials in rock pores led Klinkenberg to describe an analogy between diffusion and electrical conductivity in porous rocks back in 1951 [2]. And already in 1940, Harold Abramson and Manuel Gorin noted that 'When an electric current is applied across the living human skin, the skin may be considered to act like a system of pores through which transfer of substances like ragweed pollen extract may be achieved both by electrophoretic and by diffusion phenomena' [3]. Transport in living systems through pore structures on a much smaller scale has attracted a great deal of research in recent years as well. The selective transport of ions and small organic molecules across the cell membrane facilitates a number of functions including communication between cells, nerve conduction and signal transmission. Understanding these processes may benefit a wide range of potential applications such as selective separation, biochemical sensing, and controlled release and drug delivery processes. In Germany researchers have successfully demonstrated controlled ionic transport through nanopores functionalized with amine-terminated polymer brushes [4]. The polymer nanobrushes swell and shrink in response to changes in temperature, thus opening and closing the nanopore passage to ionic

  4. Electronic Cigarette Topography in the Natural Environment

    PubMed Central

    Morabito, P. N.; Roundtree, K. A.

    2015-01-01

    This paper presents the results of a clinical, observational, descriptive study to quantify the use patterns of electronic cigarette users in their natural environment. Previously published work regarding puff topography has been widely indirect in nature, and qualitative rather than quantitative, with the exception of three studies conducted in a laboratory environment for limited amounts of time. The current study quantifies the variation in puffing behaviors among users as well as the variation for a given user throughout the course of a day. Puff topography characteristics computed for each puffing session by each subject include the number of subject puffs per puffing session, the mean puff duration per session, the mean puff flow rate per session, the mean puff volume per session, and the cumulative puff volume per session. The same puff topography characteristics are computed across all puffing sessions by each single subject and across all subjects in the study cohort. Results indicate significant inter-subject variability with regard to puffing topography, suggesting that a range of representative puffing topography patterns should be used to drive machine-puffed electronic cigarette aerosol evaluation systems. PMID:26053075

  5. Electronic Cigarette Topography in the Natural Environment.

    PubMed

    Robinson, R J; Hensel, E C; Morabito, P N; Roundtree, K A

    2015-01-01

    This paper presents the results of a clinical, observational, descriptive study to quantify the use patterns of electronic cigarette users in their natural environment. Previously published work regarding puff topography has been widely indirect in nature, and qualitative rather than quantitative, with the exception of three studies conducted in a laboratory environment for limited amounts of time. The current study quantifies the variation in puffing behaviors among users as well as the variation for a given user throughout the course of a day. Puff topography characteristics computed for each puffing session by each subject include the number of subject puffs per puffing session, the mean puff duration per session, the mean puff flow rate per session, the mean puff volume per session, and the cumulative puff volume per session. The same puff topography characteristics are computed across all puffing sessions by each single subject and across all subjects in the study cohort. Results indicate significant inter-subject variability with regard to puffing topography, suggesting that a range of representative puffing topography patterns should be used to drive machine-puffed electronic cigarette aerosol evaluation systems.

  6. Electron transport through magnetic quantum point contacts

    NASA Astrophysics Data System (ADS)

    Day, Timothy Ellis

    Spin-based electronics, or spintronics, has generated a great deal of interest as a possible next-generation integrated circuit technology. Recent experimental and theoretical work has shown that these devices could exhibit increased processing speed, decreased power consumption, and increased integration densities as compared with conventional semiconductor devices. The spintronic device that was designed, fabricated, and tested throughout the course of this work aimed to study the generation of spin-polarized currents in semiconductors using magnetic fringe fields. The device scheme relied on the Zeeman effect in combination with a quantum mechanical barrier to generate spin-polarized currents. The Zeeman effect was used to break the degeneracy of spin-up and spin-down electrons and the quantum mechanical potential to transmit one while rejecting the other. The design was dictated by the drive to maximize the strength of the magnetic fringe field and in turn maximize the energy separation of the two spin species. The device was fabricated using advanced techniques in semiconductor processing including electron beam lithography and DC magnetron sputtering. Measurements were performed in a 3He cryostat equipped with a superconducting magnet at temperatures below 300 mK. Preliminary characterization of the device revealed magnetoconductance oscillations produced by the effect of the transverse confining potential on the density of states and the mobility. Evidence of the effect of the magnetic fringe fields on the transport properties of electrons in the device were observed in multiple device measurements. An abrupt washout of the quantized conductance steps was observed over a minute range of the applied magnetic field. The washout was again observed as electrons were shifted closer to the magnetic gates. In addition, bias spectroscopy demonstrated that the washout occurred despite stronger electron confinement, as compared to a non-magnetic split-gate. Thus, the

  7. PGR5-PGRL1-Dependent Cyclic Electron Transport Modulates Linear Electron Transport Rate in Arabidopsis thaliana.

    PubMed

    Suorsa, Marjaana; Rossi, Fabio; Tadini, Luca; Labs, Mathias; Colombo, Monica; Jahns, Peter; Kater, Martin M; Leister, Dario; Finazzi, Giovanni; Aro, Eva-Mari; Barbato, Roberto; Pesaresi, Paolo

    2016-02-01

    Plants need tight regulation of photosynthetic electron transport for survival and growth under environmental and metabolic conditions. For this purpose, the linear electron transport (LET) pathway is supplemented by a number of alternative electron transfer pathways and valves. In Arabidopsis, cyclic electron transport (CET) around photosystem I (PSI), which recycles electrons from ferrodoxin to plastoquinone, is the most investigated alternative route. However, the interdependence of LET and CET and the relative importance of CET remain unclear, largely due to the difficulties in precise assessment of the contribution of CET in the presence of LET, which dominates electron flow under physiological conditions. We therefore generated Arabidopsis mutants with a minimal water-splitting activity, and thus a low rate of LET, by combining knockout mutations in PsbO1, PsbP2, PsbQ1, PsbQ2, and PsbR loci. The resulting Δ5 mutant is viable, although mature leaves contain only ∼ 20% of wild-type naturally less abundant PsbO2 protein. Δ5 plants compensate for the reduction in LET by increasing the rate of CET, and inducing a strong non-photochemical quenching (NPQ) response during dark-to-light transitions. To identify the molecular origin of such a high-capacity CET, we constructed three sextuple mutants lacking the qE component of NPQ (Δ5 npq4-1), NDH-mediated CET (Δ5 crr4-3), or PGR5-PGRL1-mediated CET (Δ5 pgr5). Their analysis revealed that PGR5-PGRL1-mediated CET plays a major role in ΔpH formation and induction of NPQ in C3 plants. Moreover, while pgr5 dies at the seedling stage under fluctuating light conditions, Δ5 pgr5 plants are able to survive, which underlines the importance of PGR5 in modulating the intersystem electron transfer.

  8. Effects of Cu deficiency on photosynthetic electron transport

    SciTech Connect

    Droppa, M.; Terry, N.; Horvath, G.

    1984-04-01

    The role of copper (Cu) in photosynthetic electron transport was explored by using Cu deficiency in sugar beet as an experimental approach. Copper influenced electron transport at two sites in addition to plastocyanin. Under mild deficiency (0.84 nmol of Cu per cm/sup 2/ of leaf area), electron transport between the two photosystems (PS) is inhibited but not electron transport within PS I or PS II measured separately. The chlorophyll/plastoquinone ratio was normal in Cu-deficient plants. However, the breakpoint in the Arrhenius plot of electron transport was shifted towards a higher temperature. It is concluded that Cu is necessary to maintain the appropriate membrane fluidity to ensure the mobility of plastoquinone molecules to transfer electrons between the two photosystems. Under severe deficiency (0.22 nmol of Cu per cm/sup 2/ of leaf area) both PS II and PS I electron transports were inhibited and to the same extent. PS II electron transport activity could not be restored by adding artifical electron donors. Polypeptides with M/sub r/s of 28,000 and 13,500 were missing in Cu-deficient chloroplast membranes. In PS II particles prepared from normal chloroplasts of spinach, 2 atoms of Cu per reaction center are present. We conclude that Cu influences PS II electron transport either directly, by participation in electron transfer as a constituent of an electron carrier, or indirectly, via the polypeptide composition of the membrane in the PS II complex.

  9. Transportation and the Environment. Publication No. 74-2.

    ERIC Educational Resources Information Center

    Fagan, James S.

    The increasingly important role of transportation and its environmental impact is given major emphasis in this curriculum unit for secondary students. Four purposes of this unit are to describe and show (1) the historical development of transportation in America; (2) the effect of current transportation practices upon the environment; (3) some…

  10. Transportation and the Environment. Publication No. 74-2.

    ERIC Educational Resources Information Center

    Fagan, James S.

    The increasingly important role of transportation and its environmental impact is given major emphasis in this curriculum unit for secondary students. Four purposes of this unit are to describe and show (1) the historical development of transportation in America; (2) the effect of current transportation practices upon the environment; (3) some…

  11. Discovering Narrative Transportation in an Education Environment

    ERIC Educational Resources Information Center

    Miner, Eric F.

    2014-01-01

    Narrative transportation occurs when people become emotionally immersed in stories, such that they feel imaginatively conveyed into story worlds. This study investigated the lived experiences of students who encountered narrative transportation in a college classroom. It is of interest to psychologists and educational practitioners because…

  12. Discovering Narrative Transportation in an Education Environment

    ERIC Educational Resources Information Center

    Miner, Eric F.

    2014-01-01

    Narrative transportation occurs when people become emotionally immersed in stories, such that they feel imaginatively conveyed into story worlds. This study investigated the lived experiences of students who encountered narrative transportation in a college classroom. It is of interest to psychologists and educational practitioners because…

  13. Electronic Transport in Novel Graphene Nanostructures

    NASA Astrophysics Data System (ADS)

    Gannett, William Joy

    Graphene, a single sheet of sp2-bonded carbon atoms, is a two-dimensional material with an array of unique electronic, chemical, and mechanical properties. Applications including high performance transistors, chemical sensors, and composite materials have already been demonstrated. The introduction of chemical vapor deposition growth of monolayer graphene was an important step towards scalability of such devices. In addition to scalability, the exploration and application of these properties require the fabrication of high quality devices with low carrier scattering. They also require the development of unique geometries and materials combinations to exploit the highly tunable nature of graphene. This dissertation presents the synthesis of materials, fabrication of devices, and measurement of those devices for three previously unexplored types of graphene devices. The first type of device is a field effect transistor made from chemical vapor deposited (CVD) graphene on hexagonal boron nitride (hBN) substrates. We demonstrate a significant improvement in carrier mobility from hBN substrates and are able to explore the sources of scattering in CVD graphene. The second type of device, fluorinated graphene transistors, allows us to examine doping and disorder effects from fluorination of the graphene crystal as well as electronic transport through unfluorinated folds in the graphene. With the third type of device we demonstrate a new route to graphene nanoribbon devices using both hBN flakes and BN nanotubes that may reduce disorder and allow precise measurements of quantum phenomena in graphene nanoribbons.

  14. Quantum electron transport in magnetically entangled subbands

    NASA Astrophysics Data System (ADS)

    Mayer, William; Vitkalov, Sergey; Bykov, A. A.

    2017-07-01

    Transport properties of highly mobile two-dimensional (2D) electrons in symmetric GaAs quantum wells with two populated subbands placed in tilted magnetic fields are studied at high temperatures. Quantum positive magnetoresistance (QPMR) and magneto-intersubband resistance oscillations (MISO) are observed in quantizing magnetic fields, B⊥, applied perpendicular to the 2D layer. QPMR displays contributions from electrons with considerably different quantum lifetimes, τq(1 ,2 ), confirming the presence of two subbands in the studied system. MISO evolution with B⊥ agrees with the obtained quantum scattering times only if an additional reduction of the MISO magnitude is applied at small magnetic fields. This indicates the presence of a yet unknown mechanism leading to MISO damping. Application of an in-plane magnetic field produces a strong decrease of both QPMR and MISO magnitude. The reduction of QPMR is explained by spin splitting of Landau levels indicating a g factor, g ≈0.4 , which is considerably less than the g factor found in GaAs quantum well with a single subband populated. In contrast to QPMR, the decrease of MISO magnitude is largely related to the in-plane magnetic field induced entanglement between quantum levels in different subbands that, in addition, increases the MISO period.

  15. Electron scattering and transport in liquid argon

    SciTech Connect

    Boyle, G. J.; Cocks, D. G.; White, R. D.; McEachran, R. P.

    2015-04-21

    The transport of excess electrons in liquid argon driven out of equilibrium by an applied electric field is revisited using a multi-term solution of Boltzmann’s equation together with ab initio liquid phase cross-sections calculated using the Dirac-Fock scattering equations. The calculation of liquid phase cross-sections extends previous treatments to consider multipole polarisabilities and a non-local treatment of exchange, while the accuracy of the electron-argon potential is validated through comparison of the calculated gas phase cross-sections with experiment. The results presented highlight the inadequacy of local treatments of exchange that are commonly used in liquid and cluster phase cross-section calculations. The multi-term Boltzmann equation framework accounting for coherent scattering enables the inclusion of the full anisotropy in the differential cross-section arising from the interaction and the structure factor, without an a priori assumption of quasi-isotropy in the velocity distribution function. The model, which contains no free parameters and accounts for both coherent scattering and liquid phase screening effects, was found to reproduce well the experimental drift velocities and characteristic energies.

  16. Effect of Noise on DNA Sequencing via Transverse Electronic Transport

    PubMed Central

    Krems, Matt; Zwolak, Michael; Pershin, Yuriy V.; Di Ventra, Massimiliano

    2009-01-01

    Abstract Previous theoretical studies have shown that measuring the transverse current across DNA strands while they translocate through a nanopore or channel may provide a statistically distinguishable signature of the DNA bases, and may thus allow for rapid DNA sequencing. However, fluctuations of the environment, such as ionic and DNA motion, introduce important scattering processes that may affect the viability of this approach to sequencing. To understand this issue, we have analyzed a simple model that captures the role of this complex environment in electronic dephasing and its ability to remove charge carriers from current-carrying states. We find that these effects do not strongly influence the current distributions due to the off-resonant nature of tunneling through the nucleotides—a result we expect to be a common feature of transport in molecular junctions. In particular, only large scattering strengths, as compared to the energetic gap between the molecular states and the Fermi level, significantly alter the form of the current distributions. Since this gap itself is quite large, the current distributions remain protected from this type of noise, further supporting the possibility of using transverse electronic transport measurements for DNA sequencing. PMID:19804730

  17. Transportation: Environment, energy and the economy

    SciTech Connect

    Petrakis, L.

    1993-01-11

    In the US, the transportation sector consumes over one quarter of the entire energy used, almost in its entirety as petroleum products, and in quantities greater than the total US domestic oil production. The transportation sector is responsible for a significant fraction of all emissions that either prevent US cities from achieving compliance with EPA air quality standards or have serious global change implications. Finally, the GDP (Gross Domestic Product) and employment due to the sector are low and incommensurate with the high fraction of energy that the transportation sector consumes. We examine below this situation in some detail and make recommendations for improvements.

  18. Interstate waste transport -- Emotions, energy, and environment

    SciTech Connect

    Elcock, D.

    1993-12-31

    This report applies quantitative analysis to the debate of waste transport and disposal. Moving from emotions and politics back to numbers, this report estimates potential energy, employment and environmental impacts associated with disposing a ton of municipal solid waste under three different disposal scenarios that reflect interstate and intrastate options. The results help provide a less emotional, more quantitative look at interstate waste transport restrictions.

  19. Interstate waste transport -- Emotions, energy, and environment

    SciTech Connect

    Elcock, D.

    1993-01-01

    This report applies quantitative analysis to the debate of waste transport and disposal. Moving from emotions and politics back to numbers, this report estimates potential energy, employment and environmental impacts associated with disposing a ton of municipal solid waste under three different disposal scenarios that reflect interstate and intrastate options. The results help provide a less emotional, more quantitative look at interstate waste transport restrictions.

  20. Molecular orbital theory of ballistic electron transport through molecules

    NASA Astrophysics Data System (ADS)

    Ernzerhof, Matthias; Rocheleau, Philippe; Goyer, Francois

    2009-03-01

    Electron transport through molecules occurs, for instance, in STM imaging and in conductance measurements on molecular electronic devices (MEDs). To model these phenomena, we use a non-Hermitian model Hamiltonian [1] for the description of open systems that exchange current density with their environment. We derive qualitative, molecular-orbital-based rules relating molecular structure and conductance. We show how side groups attached to molecular conductors [2] can completely suppress the conductance. We discuss interference effects in aromatic molecules [3] that can also inhibit electron transport. Rules are developed [1] for the prediction of Fano resonances. All these phenomena are explained with a molecular orbital theory [1,4] for molecules attached to macroscopic reservoirs. [1] F. Goyer, M. Ernzerhof, and M. Zhuang, JCP 126, 144104 (2007); M. Ernzerhof, JCP 127, 204709 (2007). [2] M. Ernzerhof, M. Zhuang, and P. Rocheleau, JCP 123, 134704 (2005); G. C. Solomon, D Q. Andrews, R P. Van Duyne, and M A. Ratner, JACS 130, 7788 (2008). [3] M. Ernzerhof, H. Bahmann, F. Goyer, M. Zhuang, and P. Rocheleau, JCTC 2, 1291 (2006); G. C. Solomon, D. Q. Andrews, R. P. Van Duyne, and M. A. Ratner, JCP 129, 054701 (2008). [4] B.T. Pickup, P.W. Fowler, CPL 459, 198 (2008); P. Rocheleau and M. Ernzerhof, JCP, submitted.

  1. Electron transport chain defects in heart failure.

    PubMed

    Casademont, Jordi; Miró, Oscar

    2002-04-01

    In recent years, the possibility that disorders of cardiac metabolism play a role in the mechanisms that lead to ventricular dilatation and dysfunction in heart failure has attracted much attention. Electron transport chain is constituted by a series of multimeric protein complexes, located in the inner mitochondrial membranes, whose genes are distributed over both nuclear and mitochondrial DNA. Its normal function is essential to provide the energy for cardiac function. Many studies have described abnormalities in mitochondrial DNA genes encoding for electron transport chain (ETC) in dilated cardiomyopathies. In some cases, heart failure is one more or less relevant symptom among other multisystem manifestations characteristic of mitochondrial encephalomyopathies, being heart failure imputable to a primary mitochondrial disease. In the case of idiopathic dilated cardiomyopathies (IDC), many mitochondrial abnormalities have also been described using hystological, biochemical or molecular studies. The importance of such findings is under debate. The great variability in the mitochondrial abnormalities described has prompted the proposal that mitochondrial dysfunction could be a secondary phenomenon in IDC, and not a primary one. Among other possible explanations for such findings, the presence of an increased oxidative damage due to a free radical excess has been postulated. In this setting, the dysfunction of ETC could be a consequence, but also a cause of the presence of an increased free radical damage. Independently of its origin, ETC dysfunction may contribute to the persistence and worsening of heart failure. If this hypothesis, still to be proven, was certain, the modulation of cardiac metabolism could be an interesting approach to treat IDC. The precise mechanisms that lead to ventricular dilatation and dysfunction in heart failure are still nowadays poorly understood. Circumstances such as cytotoxic insults, viral infections, immune abnormalities

  2. Fate and transport of engineered nanomaterials in the environment.

    PubMed

    Lin, Daohui; Tian, Xiaoli; Wu, Fengchang; Xing, Baoshan

    2010-01-01

    With the fast development of nanotechnology, engineered nanomaterials (ENMs) will inevitably be introduced into the various environment. Increasing studies showed the toxiccity of various ENMs, which raises concerns over their fate and transport in the environment. This review focuses on advances in the research on environmental transport and fate of ENMs. Aggregation and suspension behaviors of ENMs determining their fate and transport in aqueous environment are discussed, with emphasis on the influencing factors, including natural colloids, natural organic matter, pH, and ionic strength. Studies on the transport of ENMs in porous media and its influencing factors are reviewed, and transformation and organismcleansing, as two fate routes of ENMs in the environment, are addressed. Future research directions and outlook in the environmental transport and fate of ENMs are also presented.

  3. Designing a beam transport system for RHIC's electron lens

    SciTech Connect

    Gu, X.; Pikin, A.; Okamura, M.; Fischer, W.; Luo, Y.; Gupta, R.; Hock, J.; Raparia, D.

    2011-03-28

    We designed two electron lenses to apply head-on beam-beam compensation for RHIC; they will be installed near IP10. The electron-beam transport system is an important subsystem of the entire electron-lens system. Electrons are transported from the electron gun to the main solenoid and further to the collector. The system must allow for changes of the electron beam size inside the superconducting magnet, and for changes of the electron position by 5 mm in the horizontal- and vertical-planes.

  4. Charge Transport Characterization of Novel Electronic Materials.

    NASA Astrophysics Data System (ADS)

    Marcy, Henry Orlando, 5th.

    1990-01-01

    The work presented includes analysis of electronic transport data and related measurements for the following types of materials: molecular metals and conducting polymers based upon phthalocyanine (Pc) building blocks, new composites of conducting polymers with inorganic polymeric and layered materials, and both bulk and thin film samples of the high -T_{rm c} ceramic superconductors. To successfully study such a wide spectrum of materials, the charge transport instrumentation has evolved into multiple computer-controlled experimental arrangements which process data for temperature dependent ac and dc conductivity, thermoelectric power, critical current density, and other measurements, over the temperature range of 1.5 K to 400 K. The phthalocyanine-based molecular metals and conducting polymers exhibit some of the highest reported conductivities for environmentally stable organic conductors, and possess a unique structure which is inherently resistant to large structural transformations upon donor/acceptor doping. These properties are demonstrated primarily by results for Ni(Pc)(ClO_4) _{rm y} and { (Si(Pc)O) X_{rm y}}_{rm n}. The rigidly-enforced structure of the latter system of materials allows for controllable tuning of the band-filling and hence, the charge transport properties of an organic conductor, from insulating to metal-like behavior, without any major structural alterations of the polymeric backbone. Other types of polymeric samples for which results are presented consist of composite fibers formed from the rigid rod polymers, Kevlar and PBT, "alloyed" with the (Pc)-based conducting polymers, and new microlaminates formed by intercalating various conducting polymers into the van der Waals gap of inorganic, layered host materials. Significant success has been achieved in the fabrication of superconducting films of Y-Ba-Cu-O, Bi-Sr(Pb)-Ca-Cu -O, and Tl-Ba-Ca-Cu-O by organometallic chemical vapor deposition. Results are also presented for films prepared

  5. Transition in Electron Transport in a Cylindrical Hall Thruster

    SciTech Connect

    J.B. Parker, Y. Raitses, and N.J. Fisch

    2010-06-02

    Through the use of high-speed camera and Langmuir probe measurements in a cylindrical Hall thruster, we report the discovery of a rotating spoke of increased plasma density and light emission which correlates with increased electron transport across the magnetic field. As cathode electron emission is increased, a sharp transition occurs where the spoke disappears and electron transport decreases. This suggests that a significant fraction of the electron current might be directed through the spoke.

  6. Electronic and Ionic Transport Dynamics in Organolead Halide Perovskites.

    PubMed

    Li, Dehui; Wu, Hao; Cheng, Hung-Chieh; Wang, Gongming; Huang, Yu; Duan, Xiangfeng

    2016-07-26

    Ion migration has been postulated as the underlying mechanism responsible for the hysteresis in organolead halide perovskite devices. However, the electronic and ionic transport dynamics and how they impact each other in organolead halide perovskites remain elusive to date. Here we report a systematic investigation of the electronic and ionic transport dynamics in organolead halide perovskite microplate crystals and thin films using temperature-dependent transient response measurements. Our study reveals that thermally activated ionic and electronic conduction coexist in perovskite devices. The extracted activation energies suggest that the electronic transport is easier, but ions migrate harder in microplates than in thin films, demonstrating that the crystalline quality and grain boundaries can fundamentally modify electronic and ionic transport in perovskites. These findings offer valuable insight on the electronic and ionic transport dynamics in organolead halide perovskites, which is critical for optimizing perovskite devices with reduced hysteresis and improved stability and efficiency.

  7. The induction of microsomal electron transport enzymes.

    PubMed

    Waterman, M R; Estabrook, R W

    1983-01-01

    Liver endoplasmic reticulum contains as NADPH-dependent electron transport complex where the family of hemeproteins, termed cytochrome P-450, serve as catalysts for the oxidation of a variety of different organic chemicals. The content and inventory of the types of cytochrome P-450 is readily modified following in vivo treatment of animals with 'inducing agents' such as barbiturates, steroids and polycyclic hydrocarbons. Recent studies have applied the methods of molecular biology to evaluate changes in the transcription and translation of genomic information occurring concomitant with the initiation of synthesis of various types of cytochrome P-450. The ability to isolate unique cytochrome P-450 proteins and to prepare specific antibodies now permits the study of in vitro translation of mRNA and the preparation of specific cDNAs. The present review summarizes the historic background leading to current concepts of cytochrome P-450 induction and describes recent advances in our knowledge of the regulation of cytochrome P-450 synthesis in the liver.

  8. An electron transporting blue emitter for OLED

    NASA Astrophysics Data System (ADS)

    Qi, Boyuan; Luo, Jiaxiu; Li, Suyue; Xiao, Lixin; Sun, Wenfang; Chen, Zhijian; Qu, Bo; Gong, Qihuang

    2010-11-01

    After the premier commercialization of OLED in 1997, OLED has been considered as the candidate for the next generation of flat panel display. In comparison to liquid crystal display (LCD) and plasma display panel (PDP), OLED exhibits promising merits for display, e.g., flexible, printable, micro-buildable and multiple designable. Although many efforts have been made on electroluminescent (EL) materials and devices, obtaining highly efficient and pure blue light is still a great challenge. In order to improve the emission efficiency and purity of the blue emission, a new bipolar blue light emitter, 2,7-di(2,2':6',2"-terpyridine)- 2,7-diethynyl-9,9-dioctyl-9H-fluorene (TPEF), was designed and synthesized. A blue OLED was obtained with the configuration of ITO/PEDOT/PVK:CBP:TPEF/LiF/Al. The device exhibits a turn-on voltage of 9 V and a maximum brightness of 12 cd/m2 at 15 V. The device gives a deep blue emission located at 420 nm with the Commission Internationale de l'Eclairage (CIE) coordinates of (0.17, 0.10). We also use TPEF as electron transporting material in the device of ITO/PPV/TPEF/LiF/Al, the turn-on voltage is 3 V. It is proved the current in the device was enhanced indeed by using the new material.

  9. Electron injection and transport mechanism in organic devices based on electron transport materials

    NASA Astrophysics Data System (ADS)

    Khan, M. A.; Xu, Wei; Khizar-ul-Haq; Zhang, Xiao Wen; Bai, Yu; Jiang, X. Y.; Zhang, Z. L.; Zhu, W. Q.

    2008-11-01

    Electron injection and transport in organic devices based on electron transport (ET) materials, such as 4,7- diphyenyl-1,10-phenanthroline (Bathophenanthroline BPhen), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (Bathocuproine BCP) and bipyridyl oxadiazole compound 1,3-bis [2-(2,2'-bipyridin-6-yl)-1,3,4-oxadiazol-5-yl]benzene (Bpy-OXD), have been reported. The devices are composed of ITO/ET materials (BPhen, BCP Bpy-OXD)/cathodes, where cathodes = Au, Al and Ca. Current-voltage characteristics of each ET material are performed as a function of cathodes. We have found that Ca and Al exhibit quite different J-V characteristics compared with the gold (Au) cathode. The current is more than one order of magnitude higher for the Al cathode and more than three orders of magnitude higher for Ca compared with that of the Au cathode at ~8 V for all ET materials. This is because of the relatively low energy barrier at the organic/metal interface for Ca and Al cathodes. Electron-only devices with the Au cathode show that the electron transfer limitation is located at the organic/cathode interface and the Fowler-Nordheim mechanism is qualitatively consistent with experimental data at high voltages. With Ca and Al cathodes, electron conduction is preponderant and is bulk limited. A power law dependence J ~ Vm with m > 2 is consistent with the model of trap-charge limited conduction. The total electron trap density is estimated to be ~5 × 1018 cm-3. The critical voltage (Vc) is found to be ~45 V and is almost independent of the materials.

  10. Controlling ratchet transport via a finite kicked environment

    NASA Astrophysics Data System (ADS)

    Abdulack, S. A.; Beims, M. W.; Lopes, S. R.

    2016-12-01

    We study the effects of a finite kicked environment (bath) composed of N harmonic oscillators on the particle transport in a weakly dissipative quasisymmetric potential system. The small spatial asymmetry is responsible for the appearance of directed particle transport without a net bias, known as the ratchet transport. The whole dynamics is governed by a generalized map where dissipation in the system emerges due to its interaction with the kicked environment. Distinct spectral densities are imposed to the bath oscillators and play an essential role in such models. By changing the functional form of the spectral density, we observe that the transport can be optimized or even suppressed. We show evidences that the transport optimization is related to stability properties of periodic points of the ratchet system and depends on the bath temperature. In a Markovian approach, transport can be increased or suppressed depending on the bath influence.

  11. Magnetic turbulent electron transport in a reversed field pinch

    SciTech Connect

    Schoenberg, K.; Moses, R.

    1990-01-01

    A model of magnetic turbulent electron transport is presented. The model, based on the thermal conduction theory of Rechester and Rosenbluth, entails a Boltzmann description of electron dynamics in the long mean-free-path limit and quantitatively describes the salient features of superthermal electron measurements in the RFP edge plasma. Included are predictions of the mean superthermal electron energy, current density, and power flux asymmetry. A discussion of the transport model, the assumptions implicit in the model, and the relevance of this work to more general issue of magnetic turbulent transport in toroidal systems is presented. 32 refs., 3 figs.

  12. Electron Transport in Bacillus popilliae1

    PubMed Central

    Pepper, Rollin E.; Costilow, Ralph N.

    1965-01-01

    Pepper, Rollin E. (Michigan State University, East Lansing), and Ralph N. Costilow. Electron transport in Bacillus popilliae. J. Bacteriol. 89:271–276. 1965.—Bacillus popilliae was found to be unique among aerobic microorganisms in that it was deficient in a hydrogen peroxide-scavenging system. Neither catalase nor peroxidase was found. At the same time, a system for producing hydrogen peroxide during oxidation of reduced nicotinamide adenine dinucleotide (NADH2) was consistently present in the soluble fraction of extracts of cells from older cultures. Cells harvested from 9-hr cultures did not produce a significant amount of peroxide. The soluble NADH2 oxidase was apparently a flavoprotein, since it was stimulated by flavin nucleotides, insensitive to cyanide and azide, and inhibited by Atabrine. Also, difference spectra demonstrated the presence of a reducible flavin in the soluble fraction of cell extracts. The particulate fraction of cell extracts was shown by difference spectra to contain cytochrome b1; the strong inhibition of NADH2 oxidation by cyanide, azide, and carbon monoxide indicated that a terminal cytochrome oxidase was also present. This system was also flavin-dependent, since it was strongly inhibited by Atabrine. The specific activity of the NADH2 oxidase in the particulate fraction was lower in extracts of cells from older cultures than in those from exponentially growing cultures. Cytochrome c was not found in extracts of these cells. It is believed that the increased participation of the hydrogen peroxide-generating NADH2 oxidase in cells of older cultures may be responsible for the rapid loss in cell viability noted in stationary-phase cultures. PMID:14255689

  13. Reverse electron transport effects on NADH formation and metmyoglobin reduction.

    PubMed

    Belskie, K M; Van Buiten, C B; Ramanathan, R; Mancini, R A

    2015-07-01

    The objective was to determine if NADH generated via reverse electron flow in beef mitochondria can be used for electron transport-mediated reduction and metmyoglobin reductase pathways. Beef mitochondria were isolated from bovine hearts (n=5) and reacted with combinations of succinate, NAD, and mitochondrial inhibitors to measure oxygen consumption and NADH formation. Mitochondria and metmyoglobin were reacted with succinate, NAD, and mitochondrial inhibitors to measure electron transport-mediated metmyoglobin reduction and metmyoglobin reductase activity. Addition of succinate and NAD increased oxygen consumption, NADH formation, electron transport-mediated metmyoglobin reduction, and reductase activity (p<0.05). Addition of antimycin A prevented electron flow beyond complex III, therefore, decreasing oxygen consumption and electron transport-mediated metmyoglobin reduction. Addition of rotenone prevented reverse electron flow, increased oxygen consumption, increased electron transport-mediated metmyoglobin reduction, and decreased NADH formation. Succinate and NAD can generate NADH in bovine tissue postmortem via reverse electron flow and this NADH can be used by both electron transport-mediated and metmyoglobin reductase pathways. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. 4. ENVIRONMENT, FROM SOUTHEAST, SHOWING VIRGINIA DEPARTMENT OF TRANSPORTATION BRIDGE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. ENVIRONMENT, FROM SOUTHEAST, SHOWING VIRGINIA DEPARTMENT OF TRANSPORTATION BRIDGE NO. 6023 CARRYING STATE ROUTE 646 (ADEN ROAD) OVER RAILROAD TRACKS - Virginia Department of Transportation Bridge No. 6023, Spanning Norfolk Southern tracks at State Route 646, Nokesville, Prince William County, VA

  15. 2. ENVIRONMENT, FROM NORTH, SHOWING VIRGINIA DEPARTMENT OF TRANSPORTATION BRIDGE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. ENVIRONMENT, FROM NORTH, SHOWING VIRGINIA DEPARTMENT OF TRANSPORTATION BRIDGE NO. 6051 CARRYING STATE ROUTE 673 (FEATHERBOTTOM ROAD) OVER CATOCTIN CREEK - Virginia Department of Transportation Bridge No. 6051, Spanning Catoctin Creek at State Route 673 (Featherbottom Road), Waterford, Loudoun County, VA

  16. 4. ENVIRONMENT, FROM EAST, SHOWING VIRGINIA DEPARTMENT OF TRANSPORTATION BRIDGE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. ENVIRONMENT, FROM EAST, SHOWING VIRGINIA DEPARTMENT OF TRANSPORTATION BRIDGE NO. 6051 CARRYING STATE ROUTE 673 (FEATHERBOTTOM ROAD) OVER CATOCTIN CREEK - Virginia Department of Transportation Bridge No. 6051, Spanning Catoctin Creek at State Route 673 (Featherbottom Road), Waterford, Loudoun County, VA

  17. 1. ENVIRONMENT, FROM NORTHWEST, SHOWING VIRGINIA DEPARTMENT OF TRANSPORTATION BRIDGE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. ENVIRONMENT, FROM NORTHWEST, SHOWING VIRGINIA DEPARTMENT OF TRANSPORTATION BRIDGE NO. 6051 CARRYING STATE ROUTE 673 (FEATHERBOTTOM ROAD) ACROSS CATOCTIN CREEK - Virginia Department of Transportation Bridge No. 6051, Spanning Catoctin Creek at State Route 673 (Featherbottom Road), Waterford, Loudoun County, VA

  18. 3. ENVIRONMENT, FROM SOUTH, SHOWING VIRGINIA DEPARTMENT OF TRANSPORTATION BRIDGE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. ENVIRONMENT, FROM SOUTH, SHOWING VIRGINIA DEPARTMENT OF TRANSPORTATION BRIDGE NO. 6051 CARRYING STATE ROUTE 673 (FEATHERBOTTOM ROAD) OVER CATOCTIN CREEK - Virginia Department of Transportation Bridge No. 6051, Spanning Catoctin Creek at State Route 673 (Featherbottom Road), Waterford, Loudoun County, VA

  19. Bidirectional effect of magnetic field on electronic thermal transport of metals from all-electron first-principles calculations

    NASA Astrophysics Data System (ADS)

    Yang, Jia-Yue; Yue, Sheng-Ying; Hu, Ming

    2016-12-01

    Considerable discussions have occurred about the critical role played by free electrons in the transport of heat in pure metals. In principle, any environment that can influence the dynamical behaviors of electrons would have impact on electronic thermal conductivity (κel) of metals. Over the past decades, significant progress and comprehensive understanding have been gained from theoretical, as well as experimental, investigations by taking into account the effects of various conditions, typically temperature, impurities, strain, dimensionality, interface, etc. However, the effect of external magnetic field has received less attention. In this paper, the magnetic-field dependence of electron-phonon scattering, the electron's lifetime, and κel of representative metals (Al, Ni, and Nb) are investigated within the framework of all-electron spin-density functional theory. For Al and Ni, the induced magnetization vector field and difference in electron density under external magnetic-field aggregate toward the center of unit cell, leading to the enhanced electron-phonon scattering, the damped electron's lifetime, and thus the reduced κel. On the contrary, for Nb with strong intrinsic electron-phonon interaction, the electron's lifetime and κel slightly increase as external magnetic field is enhanced. This is mainly attributed to the separately distributed magnetization vector field and difference in electron density along the corner of unit cell. This paper sheds light on the origin of influence of external magnetic field on κel for pure metals and offers a new route for robust manipulation of electronic thermal transport via applying external magnetic field.

  20. Operating systems in the air transportation environment.

    NASA Technical Reports Server (NTRS)

    Cherry, G. W.

    1971-01-01

    Consideration of the problems facing air transport at present, and to be expected in the future. In the Northeast Corridor these problems involve community acceptance, airway and airport congestion and delays, passenger acceptance, noise reduction, and improvements in low-density short-haul economics. In the development of a superior short-haul operating system, terminal-configured vs cruise-configured vehicles are evaluated. CTOL, STOL, and VTOL aircraft of various types are discussed. In the field of noise abatement, it is shown that flight procedural techniques are capable of supplementing ?quiet engine' technology.

  1. 500(deg)C electronics for harsh environments

    NASA Technical Reports Server (NTRS)

    Sadwick, Laurence P.; Hwu, R. Jennifer; Chern, J. H. Howard; Lin, Ching-Hsu; Castillo, Linda Del; Johnson, Travis

    2005-01-01

    Solid state vacuum devices (SSVDs) are a relatively new class of electronic devices. Innosys is a leading producer of high frequency SSVDs for a number of applications, including RF communications. SSVDs combine features inherent to both solid state and vacuum transistors. Electron transport can be by solid state or vacuum or both. The focus of this talk is on thermionic SSVDs, in which the primary vacuum transport is by thermionically liberated electron emission.

  2. The Near-Earth Space Radiation for Electronics Environment

    NASA Technical Reports Server (NTRS)

    Stassinopoulos, E. G.; LaBel, K. A.

    2004-01-01

    The earth's space radiation environment is described in terms of: a) charged particles as relevant to effects on spacecraft electronics, b) the nature and distribution of trapped and transiting radiation, and c) their effect on electronic components.

  3. Electrokinesis is a microbial behavior that requires extracellular electron transport

    SciTech Connect

    Harris, Howard W.; El-Naggar, Mohamed Y.; Bretschger, Orianna; Ward, Melissa J.; Romine, Margaret F.; Obraztsova, Anna; Nealson, Kenneth H.

    2010-01-05

    Shewanella species are widespread in nature, enjoying a cosmopolitan distribution in marine,freshwater, sedimentary and soil environments (1), and have attracted considerable attention in recent years because of their ability to reduce an extensive number of different electron 3 acceptors, including the solid (oxy)hydroxides of iron and manganese, such as Fe(OH)3 and MnO2, using one or more proposed mechanisms of extracellular electron transport (EET) (2, 3). The EET ability of Shewanella species is consistent with their ability to generate electric current in microbial fuel cells in the absence of exogenous electron shuttles (4). Various strategies of extracellular electron transfer have been proposed in metal-reducing microbes, including naturally-occurring (2) or biogenic (5-7) soluble mediators that ‘shuttle’ electrons from cells to acceptors, as well as direct transfer using multiheme cytochromes located on the cell exterior (8) and transfer via conductive nanowires (9-11). S. oneidensis MR-1 features several proteins that are involved with the transport of electrons to the exterior of the cell where they play an important role with regard to the reduction of solid electron acceptors such as metal oxides. These include two outer-membrane decaheme c-type cytochromes (MtrC and OmcA), a membrane spanning protein (MtrB), and two periplasmic multi-heme c-type cytochromes (MtrA and CymA). Deletion of the genes encoding any of these proteins leads to phenotypes that are greatly inhibited with regard to metal-oxide reduction and current production in microbial fuel cells (MFCs) (12, 13). The mutation of genes that code for proteins involved in the movement of cytochromes to the outer membrane also results in loss of metal-reducing phenotypes (13). The shewanellae are highly motile, by virtue of a single polar flagellum, and individual S. oneidensis MR-1 cells have been tracked swimming at speeds of up to, and sometimes over, 100 μm/sec, although the average

  4. LUNAR DUST GRAIN CHARGING BY ELECTRON IMPACT: COMPLEX ROLE OF SECONDARY ELECTRON EMISSIONS IN SPACE ENVIRONMENTS

    SciTech Connect

    Abbas, M. M.; Craven, P. D.; LeClair, A. C.; Spann, J. F.; Tankosic, D.

    2010-08-01

    Dust grains in various astrophysical environments are generally charged electrostatically by photoelectric emissions with radiation from nearby sources, or by electron/ion collisions by sticking or secondary electron emissions (SEEs). The high vacuum environment on the lunar surface leads to some unusual physical and dynamical phenomena involving dust grains with high adhesive characteristics, and levitation and transportation over long distances. Knowledge of the dust grain charges and equilibrium potentials is important for understanding a variety of physical and dynamical processes in the interstellar medium, and heliospheric, interplanetary/planetary, and lunar environments. It has been well recognized that the charging properties of individual micron-/submicron-size dust grains are expected to be substantially different from the corresponding values for bulk materials. In this paper, we present experimental results on the charging of individual 0.2-13 {mu}m size dust grains selected from Apollo 11 and 17 dust samples, and spherical silica particles by exposing them to mono-energetic electron beams in the 10-200 eV energy range. The dust charging process by electron impact involving the SEEs discussed is found to be a complex charging phenomenon with strong particle size dependence. The measurements indicate substantial differences between the polarity and magnitude of the dust charging rates of individual small-size dust grains, and the measurements and model properties of corresponding bulk materials. A more comprehensive plan of measurements of the charging properties of individual dust grains for developing a database for realistic models of dust charging in astrophysical and lunar environments is in progress.

  5. Lunary Dust Grain Charging by Electron Impact: Complex Role of Secondary Electron Emissions in Space Environments

    NASA Technical Reports Server (NTRS)

    Abbas, M. M.; Tankosic, D.; Crave, P. D.; LeClair, A.; Spann, J. F.

    2010-01-01

    Dust grains in various astrophysical environments are generally charged electrostatically by photoelectric emissions with radiation from nearby sources, or by electron/ion collisions by sticking or secondary electron emissions (SEES). The high vacuum environment on the lunar surface leads to some unusual physical and dynamical phenomena involving dust grains with high adhesive characteristics, and levitation and transportation over long distances. Knowledge of the dust grain charges and equilibrium potentials is important for understanding a variety of physical and dynamical processes in the interstellar medium, and heliospheric, interplanetary/ planetary, and lunar environments. It has been well recognized that the charging properties of individual micron-/submicron-size dust grains are expected to be substantially different from the corresponding values for bulk materials. In this paper, we present experimental results on the charging of individual 0.2-13 m size dust grains selected from Apollo 11 and 17 dust samples, and spherical silica particles by exposing them to mono-energetic electron beams in the 10-200 eV energy range. The dust charging process by electron impact involving the SEES discussed is found to be a complex charging phenomenon with strong particle size dependence. The measurements indicate substantial differences between the polarity and magnitude of the dust charging rates of individual small-size dust grains, and the measurements and model properties of corresponding bulk materials. A more comprehensive plan of measurements of the charging properties of individual dust grains for developing a database for realistic models of dust charging in astrophysical and lunar environments is in progress.

  6. Lunar Dust Grain Charging by Electron Impact: Complex Role of Secondary Electron Emissions in Space Environments

    NASA Astrophysics Data System (ADS)

    Abbas, M. M.; Tankosic, D.; Craven, P. D.; LeClair, A. C.; Spann, J. F.

    2010-08-01

    Dust grains in various astrophysical environments are generally charged electrostatically by photoelectric emissions with radiation from nearby sources, or by electron/ion collisions by sticking or secondary electron emissions (SEEs). The high vacuum environment on the lunar surface leads to some unusual physical and dynamical phenomena involving dust grains with high adhesive characteristics, and levitation and transportation over long distances. Knowledge of the dust grain charges and equilibrium potentials is important for understanding a variety of physical and dynamical processes in the interstellar medium, and heliospheric, interplanetary/planetary, and lunar environments. It has been well recognized that the charging properties of individual micron-/submicron-size dust grains are expected to be substantially different from the corresponding values for bulk materials. In this paper, we present experimental results on the charging of individual 0.2-13 μm size dust grains selected from Apollo 11 and 17 dust samples, and spherical silica particles by exposing them to mono-energetic electron beams in the 10-200 eV energy range. The dust charging process by electron impact involving the SEEs discussed is found to be a complex charging phenomenon with strong particle size dependence. The measurements indicate substantial differences between the polarity and magnitude of the dust charging rates of individual small-size dust grains, and the measurements and model properties of corresponding bulk materials. A more comprehensive plan of measurements of the charging properties of individual dust grains for developing a database for realistic models of dust charging in astrophysical and lunar environments is in progress.

  7. Kinetic theory of transport processes in partially ionized reactive plasma, II: Electron transport properties

    NASA Astrophysics Data System (ADS)

    Zhdanov, V. M.; Stepanenko, A. A.

    2016-11-01

    The previously obtained in (Zhdanov and Stepanenko, 2016) general transport equations for partially ionized reactive plasma are employed for analysis of electron transport properties in molecular and atomic plasmas. We account for both elastic and inelastic interaction channels of electrons with atoms and molecules of plasma and also the processes of electron impact ionization of neutral particles and three-body ion-electron recombination. The system of scalar transport equations for electrons is discussed and the expressions for non-equilibrium corrections to electron ionization and recombination rates and the diagonal part of the electron pressure tensor are derived. Special attention is paid to analysis of electron energy relaxation during collisions with plasma particles having internal degrees of freedom and the expression for the electron coefficient of inelastic energy losses is deduced. We also derive the expressions for electron vector and tensorial transport fluxes and the corresponding transport coefficients for partially ionized reactive plasma, which represent a generalization of the well-known results obtained by Devoto (1967). The results of numerical evaluation of contribution from electron inelastic collisions with neutral particles to electron transport properties are presented for a series of molecular and atomic gases.

  8. A deterministic computational model for the two dimensional electron and photon transport

    NASA Astrophysics Data System (ADS)

    Badavi, Francis F.; Nealy, John E.

    2014-12-01

    A deterministic (non-statistical) two dimensional (2D) computational model describing the transport of electron and photon typical of space radiation environment in various shield media is described. The 2D formalism is casted into a code which is an extension of a previously developed one dimensional (1D) deterministic electron and photon transport code. The goal of both 1D and 2D codes is to satisfy engineering design applications (i.e. rapid analysis) while maintaining an accurate physics based representation of electron and photon transport in space environment. Both 1D and 2D transport codes have utilized established theoretical representations to describe the relevant collisional and radiative interactions and transport processes. In the 2D version, the shield material specifications are made more general as having the pertinent cross sections. In the 2D model, the specification of the computational field is in terms of a distance of traverse z along an axial direction as well as a variable distribution of deflection (i.e. polar) angles θ where -π/2<θ<π/2, and corresponding symmetry is assumed for the range of azimuth angles (0<φ<2π). In the transport formalism, a combined mean-free-path and average trajectory approach is used. For candidate shielding materials, using the trapped electron radiation environments at low Earth orbit (LEO), geosynchronous orbit (GEO) and Jupiter moon Europa, verification of the 2D formalism vs. 1D and an existing Monte Carlo code are presented.

  9. Terahertz electromodulation spectroscopy of electron transport in GaN

    NASA Astrophysics Data System (ADS)

    Engelbrecht, S. G.; Arend, T. R.; Zhu, T.; Kappers, M. J.; Kersting, R.

    2015-03-01

    Time-resolved terahertz (THz) electromodulation spectroscopy is applied to investigate the high-frequency transport of electrons in gallium nitride at different doping concentrations and densities of threading dislocations. At THz frequencies, all structures reveal Drude transport. The analysis of the spectral response provides the fundamental transport properties, such as the electron scattering time and the electrons' conductivity effective mass. We observe the expected impact of ionized-impurity scattering and that scattering at threading dislocations only marginally affects the high-frequency mobility.

  10. Terahertz electromodulation spectroscopy of electron transport in GaN

    SciTech Connect

    Engelbrecht, S. G.; Arend, T. R.; Kersting, R.; Zhu, T.; Kappers, M. J.

    2015-03-02

    Time-resolved terahertz (THz) electromodulation spectroscopy is applied to investigate the high-frequency transport of electrons in gallium nitride at different doping concentrations and densities of threading dislocations. At THz frequencies, all structures reveal Drude transport. The analysis of the spectral response provides the fundamental transport properties, such as the electron scattering time and the electrons' conductivity effective mass. We observe the expected impact of ionized-impurity scattering and that scattering at threading dislocations only marginally affects the high-frequency mobility.

  11. Spin transport in tilted electron vortex beams

    SciTech Connect

    Basu, Banasri; Chowdhury, Debashree

    2014-12-10

    In this paper we have enlightened the spin related issues of tilted Electron vortex beams. We have shown that in the skyrmionic model of electron we can have the spin Hall current considering the tilted type of electron vortex beam. We have considered the monopole charge of the tilted vortex as time dependent and through the time variation of the monopole charge we can explain the spin Hall effect of electron vortex beams. Besides, with an external magnetic field we can have a spin filter configuration.

  12. Non-nuclear electron transport channels in hollow molecules

    NASA Astrophysics Data System (ADS)

    Zhao, Jin; Petek, Hrvoje

    2014-08-01

    Electron transport in inorganic semiconductors and metals occurs through delocalized bands formed by overlapping electron orbitals. Strong correlation of electronic wave functions with the ionic cores couples the electron and lattice motions, leading to efficient interaction and scattering that degrades coherent charge transport. By contrast, unoccupied electronic states at energies near the vacuum level with diffuse molecular orbitals may form nearly-free-electron bands with density maxima in non-nuclear interstitial voids, which are subject to weaker electron-phonon interaction. The position of such bands typically above the frontier orbitals, however, renders them unstable with respect to electronic interband relaxation and therefore unsuitable for charge transport. Through electronic-structure calculations, we engineer stable, non-nuclear, nearly-free-electron conduction channels in low-dimensional molecular materials by tailoring their electrostatic and polarization potentials. We propose quantum structures of graphane-derived Janus molecular sheets with spatially isolated conducting and insulating regions that potentially exhibit emergent electronic properties, as a paradigm for molecular-scale non-nuclear charge conductors; we also describe tuning of their electronic properties by application of external fields and calculate their electron-acoustic-phonon interaction.

  13. Molecular electronics: some views on transport junctions and beyond.

    PubMed

    Joachim, Christian; Ratner, Mark A

    2005-06-21

    The field of molecular electronics comprises a fundamental set of issues concerning the electronic response of molecules as parts of a mesoscopic structure and a technology-facing area of science. We will overview some important aspects of these subfields. The most advanced ideas in the field involve the use of molecules as individual logic or memory units and are broadly based on using the quantum state space of the molecule. Current work in molecular electronics usually addresses molecular junction transport, where the molecule acts as a barrier for incoming electrons: This is the fundamental Landauer idea of "conduction as scattering" generalized to molecular junction structures. Another point of view in terms of superexchange as a guiding mechanism for coherent electron transfer through the molecular bridge is discussed. Molecules generally exhibit relatively strong vibronic coupling. The last section of this overview focuses on vibronic effects, including inelastic electron tunneling spectroscopy, hysteresis in junction charge transport, and negative differential resistance in molecular transport junctions.

  14. Analysis of electron transport in the plasma of thermionic converters

    SciTech Connect

    Stoenescu, M.L.; Heinicke, P.H.

    1980-03-01

    Electron transport coefficients of a gaseous ensemble are expressed analytically as function of density, and are expressed analytically as function of temperature up to an unknown function which has to be evaluated for each specific electron-neutral atom cross section. In order to complete the analytical temperature dependence one may introduce a polynomial expansion of the function or one may derive the temperature dependence of a set of coefficients, numbering thirteen for a third approximation transport evaluation, which completely determine the transport coefficients. The latter approach is used for determining the electron transport coefficients of a cesium plasma for any ion neutral composition and any temperature between 500/sup 0/K and 3500/sup 0/K. The relation between the transport coefficients of a fully and partly ionized gas is readily available and shows that, in the classical formalism, electron-ion and electron-neutral resistivities are not additive. The present form of the transport coefficients makes possible an accurate numerical integration of transport equations eliminating lengthy computations which are frequently inaccessible. It thus provides a detailed knowledge of spatial distribution of particle and energy transport and makes possible the determination of one of the three internal voltage drops, surface barrier, sheath and plasma, which are linked together experimentally by current density versus voltage characteristics of thermionic converters.

  15. Fast electron generation and transport in a turbulent, magnetized plasma

    SciTech Connect

    Stoneking, Matthew Randall

    1994-05-01

    The nature of fast electron generation and transport in the Madison Symmetric Torus (MST) reversed field pinch (RFP) is investigated using two electron energy analyzer (EEA) probes and a thermocouple calorimeter. The parallel velocity distribution of the fast electron population is well fit by a drifted Maxwellian distribution with temperature of about 100 eV and drift velocity of about 2 x 106 m/s. Cross-calibration of the EEA with the calorimeter provides a measurement of the fast electron perpendicular temperature of 30 eV, much lower than the parallel temperature, and is evidence that the kinetic dynamo mechanism (KDT) is not operative in MST. The fast electron current is found to match to the parallel current at the edge, and the fast electron density is about 4 x 1011 cm-3 independent of the ratio of the applied toroidal electric field to the critical electric field for runaways. First time measurements of magnetic fluctuation induced particle transport are reported. By correlating electron current fluctuations with radial magnetic fluctuations the transported flux of electrons is found to be negligible outside r/a~0.9, but rises the level of the expected total particle losses inside r/a~0.85. A comparison of the measured diffusion coefficient is made with the ausilinear stochastic diffusion coefficient. Evidence exists that the reduction of the transport is due to the presence of a radial ambipolar electric field of magnitude 500 V/m, that acts to equilibrate the ion and electron transport rates. The convective energy transport associated with the measured particle transport is large enough to account for the observed magnetic fluctuation induced energy transport in MST.

  16. Ballistic electron transport in wrinkled superlattices

    NASA Astrophysics Data System (ADS)

    Mitran, T. L.; Nemnes, G. A.; Ion, L.; Dragoman, Daniela

    2016-07-01

    Inspired by the problem of elastic wave scattering on wrinkled interfaces, we studied the scattering of ballistic electrons on a wrinkled potential energy region. The electron transmission coefficient depends on both wrinkle amplitude and periodicity, having different behaviors for positive and negative scattering potential energies. For scattering on potential barriers, minibands appear in the electron transmission, as in superlattices, whereas for scattering on periodic potential wells the transmission coefficient has a more complex form. Besides suggesting that tuning of electron transmission is possible by modifying the scattering potential via voltages on wrinkled gate electrodes, our results emphasize the analogies between ballistic electrons and elastic waves even in scattering problems on non-typical configurations.

  17. Electron transport-dependent taxis in Rhodobacter sphaeroides.

    PubMed

    Gauden, D E; Armitage, J P

    1995-10-01

    Rhodobacter sphaeroides showed chemotaxis to the terminal electron acceptors oxygen and dimethyl sulfoxide, and the responses to these effectors were shown to be influenced by the relative activities of the different electron transport pathways. R. sphaeroides cells tethered by their flagella showed a step-down response to a decrease in the oxygen or dimethyl sulfoxide concentration when using them as terminal acceptors. Bacteria using photosynthetic electron transport, however, showed a step-down response to oxygen addition. Addition of the proton ionophore carbonyl cyanide 4-trifluoromethoxyphenylhydrazone did not cause a transient behavioral response, although it decreased the electrochemical proton gradient (delta p) and increased the rate of electron transport. However, removal of the ionophore, which caused an increase in delta p and a decrease in the electron transport rate, resulted in a step-down response. Together, these data suggest that behavioral responses of R. sphaeroides to electron transport effectors are caused by changes in the rate of electron transport rather than changes in delta p.

  18. Hot electron transport and current sensing

    NASA Astrophysics Data System (ADS)

    Abraham, Mathew Cheeran

    The effect of hot electrons on momentum scattering rates in a two-dimensional electron gas is critically examined. It is shown that with hot electrons it is possible to explore the temperature dependence of individual scattering mechanisms not easily probed under equilibrium conditions; both the Bloch-Gruneisen (BG) phonon scattering phenomena and the reduction in impurity scattering are clearly observed. The theoretical calculations are consistent with the results obtained from hot electrons experiments. As a function of bias current, a resistance peak is formed in a 2DEG if the low temperature impurity limited mobilities muI( T = 0) is comparable to muph(TBG ) the phonon limited mobility at the critical BG temperature. In this case, as the bias current is increased, the electron temperature Te rises due to Joule heating and the rapid increase in phonon scattering can be detected before the effect of the reduction in impurity scattering sets in. If muI(T = 0) << muph(TBG), there is no peak in resistance because the impurity scattering dominates sufficiently and its reduction has a much stronger effect on the total resistance than the rise in phonon scattering. Furthermore, knowing the momentum relaxation rates allows us to analyze the possible interplay between electron-electron and electron-boundary scattering. The prediction that a Knudsen to Poiseuille (KP) transition similar to that of a classical gas can occur in electron flow [26] is examined for the case of a wire defined in a 2DEG. Concurrently, an appropriate current imaging technique to detect this transition is sought. A rigorous evaluation of magnetic force microscopy (MFM) as a possible candidate to detect Poiseuille electronic flow was conducted, and a method that exploits the mechanical resonance of the MFM cantilever was implemented to significantly improve its current sensitivity.

  19. Four papers on transportation and the environment

    NASA Astrophysics Data System (ADS)

    Roth, Kevin Daniel

    The main essay of this thesis, found in the first chapter, examines how two policies that are a priori equivalent, fuel economy standards and feebates, interact differently with complementary policies that also attempt to improve fuel economy. To examine these interactions I build a general equilibrium model of the automobile market that allows manufacturers to trade off horsepower, weight, and fuel economy of vehicles along a production possibility frontier (PPF). I also estimate household demand for vehicles and miles for a simulation model that includes the used car and scrappage markets. This model allows me to simulate the interaction of a research and development policy that increases the PPF of domestic firms, or a tax credit that increases demand for efficient vehicles, with either a CAFE standard or feebate. I find that vehicle emissions increase under all these interactions but the effects are muted under the feebate because it allows fuel economy to improve by 0.60% to 1.88%, while CAFE, by targeting an average fuel economy, will always offset these uncoordinated complementary policies. The second essay examines transportation systems with unpriced congestion where single-occupant low-emission vehicles are allowed into high occupancy vehicle (HOV) lanes to encourage their adoption exacerbates congestion costs for carpoolers. The resulting welfare effects of the policy are negative, with environmental benefits overwhelmingly dominated by the increased congestion costs. Exploiting the introduction of the Clean Air Vehicle Stickers policy in California with a regression discontinuity design, our results imply a best-case cost of 124 per ton of reductions in greenhouse gases, 606,000 dollars per ton of nitrogen oxides reduction, and $505,000 dollars per ton of hydrocarbon reduction, exceeding those of other options readily available to policymakers. The third essay examines the 'Energy Paradox.' From previous literature, it can be found that consumers tend

  20. Non-nuclear Electron Transport Channels in Hollow Molecules

    SciTech Connect

    Zhao, Jin; Petek, Hrvoje

    2014-08-15

    Electron transport in inorganic semiconductors and metals occurs through delocalized bands formed by overlapping electron orbitals. Strong correlation of electronic wave functions with the ionic cores couples the electron and lattice motions, leading to efficient interaction and scattering that degrades coherent charge transport. By contrast, unoccupied electronic states at energies near the vacuum level with diffuse molecular orbitals may form nearly-free-electron bands with density maxima in non-nuclear interstitial voids, which are subject to weaker electron-phonon interaction. The position of such bands typically above the frontier orbitals, however, renders them unstable with respect to electronic interband relaxation and therefore unsuitable for charge transport. Through electronic-structure calculations, we engineer stable, non-nuclear, nearly-free-electron conduction channels in low-dimensional molecular materials by tailoring their electrostatic and polarization potentials. We propose quantum structures of graphane-derived Janus molecular sheets with spatially isolated conducting and insulating regions that potentially exhibit emergent electronic properties, as a paradigm for molecular-scale non-nuclear charge conductors; we also describe tuning of their electronic properties by application of external fields and calculate their electron–acoustic-phonon interaction.

  1. An ab initio electronic transport database for inorganic materials

    NASA Astrophysics Data System (ADS)

    Ricci, Francesco; Chen, Wei; Aydemir, Umut; Snyder, G. Jeffrey; Rignanese, Gian-Marco; Jain, Anubhav; Hautier, Geoffroy

    2017-07-01

    Electronic transport in materials is governed by a series of tensorial properties such as conductivity, Seebeck coefficient, and effective mass. These quantities are paramount to the understanding of materials in many fields from thermoelectrics to electronics and photovoltaics. Transport properties can be calculated from a material's band structure using the Boltzmann transport theory framework. We present here the largest computational database of electronic transport properties based on a large set of 48,000 materials originating from the Materials Project database. Our results were obtained through the interpolation approach developed in the BoltzTraP software, assuming a constant relaxation time. We present the workflow to generate the data, the data validation procedure, and the database structure. Our aim is to target the large community of scientists developing materials selection strategies and performing studies involving transport properties.

  2. Electronic and vibrational hopping transport in boron carbides

    SciTech Connect

    Emin, D. )

    1991-07-01

    General concepts of hopping-type transport and localization are reviewed. Disorder, electronic correlations and atomic displacements, effects ignored in electronic band structure calculations, foster localization of electronic charge carriers. Examples are given that illustrate the efficacy of these effects in producing localization. This introduction is followed by a brief discussion of the relation between hopping-type transport and localization. The fundamentals of the formation, localization, and hopping transport of small polarons and/or bipolarons is then described. Electronic transport in boron carbides is presented as an example of the adiabatic hopping of small bipolarons. Finally, the notion of vibrational hopping is introduced. The high-temperature thermal diffusion in boron carbides is presented as a potential application of this idea.

  3. Transport of electrons in lead oxide studied by CELIV technique

    NASA Astrophysics Data System (ADS)

    Semeniuk, O.; Juska, G.; Oelerich, J. O.; Jandieri, K.; Baranovskii, S. D.; Reznik, A.

    2017-01-01

    Although polycrystalline lead oxide (PbO) has a long history of application in optoelectronics and imaging, the transport mechanism for electrons in this material has not yet been clarified. Using the photo-generated charge extraction by linear increasing voltage (photo-CELIV) technique, we provide the temperature- and field-dependences of electron mobility in poly-PbO. It is found that electrons undergo dispersive transport, i.e. their mobility decreases in the course of time. Multiple trapping of electrons from the conduction band into the developed band tail is revealed as the dominant transport mechanism. This differs dramatically from the dispersive transport of holes in the same material, dominated by topological factors and not by energy disorder.

  4. Transport of runaway and thermal electrons due to magnetic microturbulence

    SciTech Connect

    Mynick, H.E.; Strachan, J.D.

    1981-04-01

    The ratio of the runaway electron confinement to thermal electron energy confinement is derived for tokamaks where both processes are determined by free streaming along stochastic magnetic field lines. The runaway electron confinement is enhanced at high runaway electron energies due to phase averaging over the magnetic perturbations when the runaway electron drift surfaces are displaced from the magnetic surfaces. Comparison with experimental data from LT-3, Ormak, PLT, ST, and TM-3 indicates that magnetic stochasticity may explain the relative transport rates of runaways and thermal electron energy.

  5. Numerical evidence for robustness of environment-assisted quantum transport.

    PubMed

    Shabani, A; Mohseni, M; Rabitz, H; Lloyd, S

    2014-04-01

    Recent theoretical studies show that decoherence process can enhance transport efficiency in quantum systems. This effect is known as environment-assisted quantum transport (ENAQT). The role of ENAQT in optimal quantum transport is well investigated; however, it is less known how robust ENAQT is with respect to variations in the system or its environment characteristic. Toward answering this question, we simulated excitonic energy transfer in Fenna-Matthews-Olson photosynthetic complex. We found that ENAQT is robust with respect to many relevant parameters of environmental interactions and Frenkel-exciton Hamiltonians, including reorganization energy, bath-frequency cutoff, temperature, initial excitations, dissipation rate, trapping rate, disorders, and dipole moments orientations. Our study suggests that the ENAQT phenomenon can be exploited in robust design of highly efficient quantum transport systems.

  6. Simulation of electron thermal transport in H-mode discharges

    SciTech Connect

    Rafiq, T.; Pankin, A. Y.; Bateman, G.; Kritz, A. H.; Halpern, F. D.

    2009-03-15

    Electron thermal transport in DIII-D H-mode tokamak plasmas [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] is investigated by comparing predictive simulation results for the evolution of electron temperature profiles with experimental data. The comparison includes the entire profile from the magnetic axis to the bottom of the pedestal. In the simulations, carried out using the automated system for transport analysis (ASTRA) integrated modeling code, different combinations of electron thermal transport models are considered. The combinations include models for electron temperature gradient (ETG) anomalous transport and trapped electron mode (TEM) anomalous transport, as well as a model for paleoclassical transport [J. D. Callen, Nucl. Fusion 45, 1120 (2005)]. It is found that the electromagnetic limit of the Horton ETG model [W. Horton et al., Phys. Fluids 31, 2971 (1988)] provides an important contribution near the magnetic axis, which is a region where the ETG mode in the GLF23 model [R. E. Waltz et al., Phys. Plasmas 4, 2482 (1997)] is below threshold. In simulations of DIII-D discharges, the observed shape of the H-mode edge pedestal is produced when transport associated with the TEM component of the GLF23 model is suppressed and transport given by the paleoclassical model is included. In a study involving 15 DIII-D H-mode discharges, it is found that with a particular combination of electron thermal transport models, the average rms deviation of the predicted electron temperature profile from the experimental profile is reduced to 9% and the offset to -4%.

  7. Simulation of electron thermal transport in H-mode discharges

    NASA Astrophysics Data System (ADS)

    Rafiq, T.; Pankin, A. Y.; Bateman, G.; Kritz, A. H.; Halpern, F. D.

    2009-03-01

    Electron thermal transport in DIII-D H-mode tokamak plasmas [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] is investigated by comparing predictive simulation results for the evolution of electron temperature profiles with experimental data. The comparison includes the entire profile from the magnetic axis to the bottom of the pedestal. In the simulations, carried out using the automated system for transport analysis (ASTRA) integrated modeling code, different combinations of electron thermal transport models are considered. The combinations include models for electron temperature gradient (ETG) anomalous transport and trapped electron mode (TEM) anomalous transport, as well as a model for paleoclassical transport [J. D. Callen, Nucl. Fusion 45, 1120 (2005)]. It is found that the electromagnetic limit of the Horton ETG model [W. Horton et al., Phys. Fluids 31, 2971 (1988)] provides an important contribution near the magnetic axis, which is a region where the ETG mode in the GLF23 model [R. E. Waltz et al., Phys. Plasmas 4, 2482 (1997)] is below threshold. In simulations of DIII-D discharges, the observed shape of the H-mode edge pedestal is produced when transport associated with the TEM component of the GLF23 model is suppressed and transport given by the paleoclassical model is included. In a study involving 15 DIII-D H-mode discharges, it is found that with a particular combination of electron thermal transport models, the average rms deviation of the predicted electron temperature profile from the experimental profile is reduced to 9% and the offset to -4%.

  8. Relativistic Electron Beam Transport and Characteristics in Solid Density Plasmas

    SciTech Connect

    Snavely, R A; King, J; Freeman, R R; Hatchett, S; Key, M H; Koch, J; Langdon, A B; Lasinsky, B; MacKinnon, A; Wilks, S; Stephens, R

    2003-08-13

    The transport of intense relativistic beams in solid density plasma presently is actively being studied in laser laboratories around the world. The correct understanding of the transport enables further application of fast laser driven electrons to a host of interesting uses. Advanced x-ray sources, proton and ion beam generation and plasma heating in fast ignitor fusion all are owed their eventual utility to this transport. We report on measurements of relativistic transport over the whole of the transport region, via analysis of x-ray emission. Our experiments cover laser powers from Terawatt to Petawatt. Advances in transverse imaging of fluorescent k-alpha x-rays generated along the electron beam path are used to diagnose the electron emission. Additionally the spatial pattern of Bremsstrahlung x-rays provides clues into the physics of electron transport in above Alfven current limit beams. Issues regarding the electron distribution function will be discussed in light of possible electron transport anomalies. The initial experiments performed on the Nova Petawatt Laser System were those associated with determining the nature of the electrons and x-rays in this relativistic regime especially those useful for advanced radiography sources suitable for diagnostic use in dense high-Z dynamic processes or as the driver of a relativistic electron source in the Fast-Ignitor Inertial Confinement fusion concept. The development of very large arrays of thermoluminescent detectors is detailed along with their response. The characteristic pattern of x-rays and their intensity is found from detailed analysis of the TLD detector array data. Peak intensities as high as 2 Rads at 1 meter were measured with these shielded TLD arrays. An average energy yield of x-rays of 11 Joules indicates a very large fraction of 45-55% of the laser energy is absorbed into relativistic electrons. The pattern of x-ray distribution lends insight to the initial relativistic electron distribution

  9. Time-Resolved Hot Electron Transport in Electronic Devices

    DTIC Science & Technology

    1988-12-01

    wavevector in the barrier). For the heavy holes tunneling from QWI to QW2 the k’s are k2 = (2mb(VI-E) A2" k3 = (2m 3E/ hZJ . For the electrons tunneling from...Laser-Exci, td bem~onductors,’ Prog. Quantum Electron. 9, 3 (1984). 9 G. D. Sanders and Yia-Chung Chang, "Theory of Photoabsorption in Modulation-Doped

  10. RHIC electron lens beam transport system design considerations

    SciTech Connect

    Gu, X.; Pikin, A.; Okamura, M.; Fischer, W.; Luo, Y.; Gupta, R.; Hock, J.; Jain, A.; Raparia, D.

    2010-10-01

    To apply head-on beam-beam compensation for RHIC, two electron lenses are designed and will be installed at IP10. Electron beam transport system is one of important subsystem, which is used to transport electron beam from electron gun side to collector side. This system should be able to change beam size inside superconducting magnet and control beam position with 5 mm in horizontal and vertical plane. Some other design considerations for this beam transport system are also reported in this paper. The head-on beam-beam effect is one of important nonlinear source in storage ring and linear colliders, which have limited the luminosity improvement of many colliders, such as SppS, Tevatron and RHIC. In order to enhance the performance of colliders, beam-beam effects can be compensated with direct space charge compensation, indirect space charge compensation or betatron phase cancellation scheme. Like other colliders, indirect space charge compensation scheme (Electron Lens) was also proposed for Relativistic Heavy Ion Collider (RHIC) beam-beam compensation at Brookhaven National Laboratory. The two similar electron lenses are located in IR10 between the DX magnets. One RHIC electron lens consists of one DC electron gun, one superconducting magnet, one electron collector and beam transport system.

  11. Energy-filtered cold electron transport at room temperature

    PubMed Central

    Bhadrachalam, Pradeep; Subramanian, Ramkumar; Ray, Vishva; Ma, Liang-Chieh; Wang, Weichao; Kim, Jiyoung; Cho, Kyeongjae; Koh, Seong Jin

    2014-01-01

    Fermi-Dirac electron thermal excitation is an intrinsic phenomenon that limits functionality of various electron systems. Efforts to manipulate electron thermal excitation have been successful when the entire system is cooled to cryogenic temperatures, typically <1 K. Here we show that electron thermal excitation can be effectively suppressed at room temperature, and energy-suppressed electrons, whose energy distribution corresponds to an effective electron temperature of ~45 K, can be transported throughout device components without external cooling. This is accomplished using a discrete level of a quantum well, which filters out thermally excited electrons and permits only energy-suppressed electrons to participate in electron transport. The quantum well (~2 nm of Cr2O3) is formed between source (Cr) and tunnelling barrier (SiO2) in a double-barrier-tunnelling-junction structure having a quantum dot as the central island. Cold electron transport is detected from extremely narrow differential conductance peaks in electron tunnelling through CdSe quantum dots, with full widths at half maximum of only ~15 mV at room temperature. PMID:25204839

  12. SUPPRESSION OF ENERGETIC ELECTRON TRANSPORT IN FLARES BY DOUBLE LAYERS

    SciTech Connect

    Li, T. C.; Drake, J. F.; Swisdak, M.

    2012-09-20

    During flares and coronal mass ejections, energetic electrons from coronal sources typically have very long lifetimes compared to the transit times across the systems, suggesting confinement in the source region. Particle-in-cell simulations are carried out to explore the mechanisms of energetic electron transport from the corona to the chromosphere and possible confinement. We set up an initial system of pre-accelerated hot electrons in contact with ambient cold electrons along the local magnetic field and let it evolve over time. Suppression of transport by a nonlinear, highly localized electrostatic electric field (in the form of a double layer) is observed after a short phase of free-streaming by hot electrons. The double layer (DL) emerges at the contact of the two electron populations. It is driven by an ion-electron streaming instability due to the drift of the back-streaming return current electrons interacting with the ions. The DL grows over time and supports a significant drop in temperature and hence reduces heat flux between the two regions that is sustained for the duration of the simulation. This study shows that transport suppression begins when the energetic electrons start to propagate away from a coronal acceleration site. It also implies confinement of energetic electrons with kinetic energies less than the electrostatic energy of the DL for the DL lifetime, which is much longer than the electron transit time through the source region.

  13. Cyclic electron transport around photosystem I: genetic approaches.

    PubMed

    Shikanai, Toshiharu

    2007-01-01

    The light reactions in photosynthesis convert light energy into chemical energy in the form of ATP and drive the production of NADPH from NADP+. The reactions involve two types of electron flow in the chloroplast. While linear electron transport generates both ATP and NADPH, photosystem I cyclic electron transport is exclusively involved in ATP synthesis. The physiological significance of photosystem I cyclic electron transport has been underestimated, and our knowledge of the machineries involved remains very limited. However, recent genetic approaches using Arabidopsis thaliana have clarified the essential functions of this electron flow in both photoprotection and photosynthesis. Based on several lines of evidence presented here, it is necessary to reconsider the fundamental mechanisms of chloroplast energetics.

  14. Nano-structured electron transporting materials for perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Liu, Hefei; Huang, Ziru; Wei, Shiyuan; Zheng, Lingling; Xiao, Lixin; Gong, Qihuang

    2016-03-01

    Organic-inorganic hybrid perovskite solar cells have been developing rapidly in the past several years, and their power conversion efficiency has reached over 20%, nearing that of polycrystalline silicon solar cells. Because the diffusion length of the hole in perovskites is longer than that of the electron, the performance of the device can be improved by using an electron transporting layer, e.g., TiO2, ZnO and TiO2/Al2O3. Nano-structured electron transporting materials facilitate not only electron collection but also morphology control of the perovskites. The properties, morphology and preparation methods of perovskites are reviewed in the present article. A comprehensive understanding of the relationship between the structure and property will benefit the precise control of the electron transporting process and thus further improve the performance of perovskite solar cells.

  15. Nano-structured electron transporting materials for perovskite solar cells.

    PubMed

    Liu, Hefei; Huang, Ziru; Wei, Shiyuan; Zheng, Lingling; Xiao, Lixin; Gong, Qihuang

    2016-03-28

    Organic-inorganic hybrid perovskite solar cells have been developing rapidly in the past several years, and their power conversion efficiency has reached over 20%, nearing that of polycrystalline silicon solar cells. Because the diffusion length of the hole in perovskites is longer than that of the electron, the performance of the device can be improved by using an electron transporting layer, e.g., TiO2, ZnO and TiO2/Al2O3. Nano-structured electron transporting materials facilitate not only electron collection but also morphology control of the perovskites. The properties, morphology and preparation methods of perovskites are reviewed in the present article. A comprehensive understanding of the relationship between the structure and property will benefit the precise control of the electron transporting process and thus further improve the performance of perovskite solar cells.

  16. Large electron screening effect in different environments

    SciTech Connect

    Cvetinović, Aleksandra Lipoglavšek, Matej; Markelj, Sabina; Vesić, Jelena

    2015-10-15

    Electron screening effect was studied in the {sup 1}H({sup 7}Li,α){sup 4}He, {sup 1}H({sup 11}B,α){sup 4}He and {sup 1}H({sup 19}F,αγ){sup 16}O reactions in inverse kinematics on different hydrogen implanted targets. Results show large electron screening potentials strongly dependent on the proton number Z of the projectile.

  17. Large electron screening effect in different environments

    NASA Astrophysics Data System (ADS)

    Cvetinović, Aleksandra; Lipoglavsek, Matej; Markelj, Sabina; Vesić, Jelena

    2016-05-01

    Electron screening effect was studied on different hydrogen containing targets with the 7Li, 11B and 19F ion beams. Results show large electron screening potentials strongly dependent on the proton number Z of the projectile. The largest ever measured screening potential with the value about a factor of 50 above the calculations from the model in adiabatic limit was observed in the graphite target containing hydrogen as an impurity.

  18. Recent progress in understanding electron thermal transport in NSTX

    NASA Astrophysics Data System (ADS)

    Ren, Y.; Belova, E.; Gorelenkov, N.; Guttenfelder, W.; Kaye, S. M.; Mazzucato, E.; Peterson, J. L.; Smith, D. R.; Stutman, D.; Tritz, K.; Wang, W. X.; Yuh, H.; Bell, R. E.; Domier, C. W.; LeBlanc, B. P.

    2017-07-01

    The anomalous level of electron thermal transport inferred in magnetically confined configurations is one of the most challenging problems for the ultimate realization of fusion power using toroidal devices: tokamaks, spherical tori and stellarators. It is generally believed that plasma instabilities driven by the abundant free energy in fusion plasmas are responsible for the electron thermal transport. The National Spherical Torus eXperiment (NSTX) (Ono et al 2000 Nucl. Fusion 40 557) provides a unique laboratory for studying plasma instabilities and their relation to electron thermal transport due to its low toroidal field, high plasma beta, low aspect ratio and large E× B flow shear. Recent findings on NSTX have shown that multiple instabilities are required to explain observed electron thermal transport, given the wide range of equilibrium parameters due to different operational scenarios and radial regions in fusion plasmas. Here we review the recent progresses in understanding anomalous electron thermal transport in NSTX and focus on mechanisms that could drive electron thermal transport in the core region. The synergy between experiment and theoretical/numerical modeling is essential to achieving these progresses. The plans for newly commissioned NSTX-Upgrade will also be discussed.

  19. Recent progress in understanding electron thermal transport in NSTX

    DOE PAGES

    Ren, Y.; Belova, E.; Gorelenkov, N.; ...

    2017-03-10

    The anomalous level of electron thermal transport inferred in magnetically confined configurations is one of the most challenging problems for the ultimate realization of fusion power using toroidal devices: tokamaks, spherical tori and stellarators. It is generally believed that plasma instabilities driven by the abundant free energy in fusion plasmas are responsible for the electron thermal transport. The National Spherical Torus eXperiment (NSTX) (Ono et al 2000 Nucl. Fusion 40 557) provides a unique laboratory for studying plasma instabilities and their relation to electron thermal transport due to its low toroidal field, high plasma beta, low aspect ratio and largemore » ExB flow shear. Recent findings on NSTX have shown that multiple instabilities are required to explain observed electron thermal transport, given the wide range of equilibrium parameters due to different operational scenarios and radial regions in fusion plasmas. Here we review the recent progresses in understanding anomalous electron thermal transport in NSTX and focus on mechanisms that could drive electron thermal transport in the core region. The synergy between experiment and theoretical/ numerical modeling is essential to achieving these progresses. The plans for newly commissioned NSTX-Upgrade will also be discussed.« less

  20. Characterizing transport through a crowded environment with different obstacle sizes

    NASA Astrophysics Data System (ADS)

    Ellery, Adam J.; Simpson, Matthew J.; McCue, Scott W.; Baker, Ruth E.

    2014-02-01

    Transport through crowded environments is often classified as anomalous, rather than classical, Fickian diffusion. Several studies have sought to describe such transport processes using either a continuous time random walk or fractional order differential equation. For both these models the transport is characterized by a parameter α, where α = 1 is associated with Fickian diffusion and α < 1 is associated with anomalous subdiffusion. Here, we simulate a single agent migrating through a crowded environment populated by impenetrable, immobile obstacles and estimate α from mean squared displacement data. We also simulate the transport of a population of such agents through a similar crowded environment and match averaged agent density profiles to the solution of a related fractional order differential equation to obtain an alternative estimate of α. We examine the relationship between our estimate of α and the properties of the obstacle field for both a single agent and a population of agents; we show that in both cases, α decreases as the obstacle density increases, and that the rate of decrease is greater for smaller obstacles. Our work suggests that it may be inappropriate to model transport through a crowded environment using widely reported approaches including power laws to describe the mean squared displacement and fractional order differential equations to represent the averaged agent density profiles.

  1. Characterizing transport through a crowded environment with different obstacle sizes.

    PubMed

    Ellery, Adam J; Simpson, Matthew J; McCue, Scott W; Baker, Ruth E

    2014-02-07

    Transport through crowded environments is often classified as anomalous, rather than classical, Fickian diffusion. Several studies have sought to describe such transport processes using either a continuous time random walk or fractional order differential equation. For both these models the transport is characterized by a parameter α, where α = 1 is associated with Fickian diffusion and α < 1 is associated with anomalous subdiffusion. Here, we simulate a single agent migrating through a crowded environment populated by impenetrable, immobile obstacles and estimate α from mean squared displacement data. We also simulate the transport of a population of such agents through a similar crowded environment and match averaged agent density profiles to the solution of a related fractional order differential equation to obtain an alternative estimate of α. We examine the relationship between our estimate of α and the properties of the obstacle field for both a single agent and a population of agents; we show that in both cases, α decreases as the obstacle density increases, and that the rate of decrease is greater for smaller obstacles. Our work suggests that it may be inappropriate to model transport through a crowded environment using widely reported approaches including power laws to describe the mean squared displacement and fractional order differential equations to represent the averaged agent density profiles.

  2. Computer modeling of electron and proton transport in chloroplasts.

    PubMed

    Tikhonov, Alexander N; Vershubskii, Alexey V

    2014-07-01

    Photosynthesis is one of the most important biological processes in biosphere, which provides production of organic substances from atmospheric CO2 and water at expense of solar energy. In this review, we contemplate computer models of oxygenic photosynthesis in the context of feedback regulation of photosynthetic electron transport in chloroplasts, the energy-transducing organelles of the plant cell. We start with a brief overview of electron and proton transport processes in chloroplasts coupled to ATP synthesis and consider basic regulatory mechanisms of oxygenic photosynthesis. General approaches to computer simulation of photosynthetic processes are considered, including the random walk models of plastoquinone diffusion in thylakoid membranes and deterministic approach to modeling electron transport in chloroplasts based on the mass action law. Then we focus on a kinetic model of oxygenic photosynthesis that includes key stages of the linear electron transport, alternative pathways of electron transfer around photosystem I (PSI), transmembrane proton transport and ATP synthesis in chloroplasts. This model includes different regulatory processes: pH-dependent control of the intersystem electron transport, down-regulation of photosystem II (PSII) activity (non-photochemical quenching), the light-induced activation of the Bassham-Benson-Calvin (BBC) cycle. The model correctly describes pH-dependent feedback control of electron transport in chloroplasts and adequately reproduces a variety of experimental data on induction events observed under different experimental conditions in intact chloroplasts (variations of CO2 and O2 concentrations in atmosphere), including a complex kinetics of P700 (primary electron donor in PSI) photooxidation, CO2 consumption in the BBC cycle, and photorespiration. Finally, we describe diffusion-controlled photosynthetic processes in chloroplasts within the framework of the model that takes into account complex architecture of

  3. Chiral electron transport: Scattering through helical potentials

    NASA Astrophysics Data System (ADS)

    Yeganeh, Sina; Ratner, Mark A.; Medina, Ernesto; Mujica, Vladimiro

    2009-07-01

    We present a model for the transmission of spin-polarized electrons through oriented chiral molecules, where the chiral structure is represented by a helix. The scattering potential contains a confining term and a spin-orbit contribution that is responsible for the spin-dependent scattering of electrons by the molecular target. The differential scattering cross section is calculated for right- and left-handed helices and for arbitrary electron spin polarizations. We apply our model to explain chiral effects in the intensity of photoemitted polarized electrons transmitted through thin organic layers. These are molecular interfaces that exhibit spin-selective scattering with surprisingly large asymmetry factors as well as a number of remarkable magnetic properties. In our model, differences in intensity are generated by the preferential transmission of electron beams whose polarization is oriented in the same direction as the sense of advance of the helix. This model can be easily extended to the Landauer regime of conductance where conductance is due to elastic scattering, so that we can consider the conductance of chiral molecular junctions.

  4. Persistence and transport potential of chemicals in a multimedia environment

    SciTech Connect

    van de Meent, D.; McKone, T.E.; Parkerton, T.; Matthies, M.; Scheringer, M.; Wania, F.; Purdy, R.; Bennett, D.H.

    2000-02-01

    Persistence in the environment and potential for long-range transport are related since time in the environment is required for transport. A persistent chemical will travel longer distances than a reactive chemical that shares similar chemical properties. Scheringer (1997) has demonstrated the correlation between persistence and transport distance for different organic chemicals. However, this correlation is not sufficiently robust to predict one property from the other. Specific chemicals that are persistent mayor may not exhibit long-range transport potential. Persistence and long-range transport also present different societal concerns. Persistence concerns relate to the undesired possibility that chemicals produced and used now may somehow negatively affect future generations. Long-range transport concerns relate to the undesired presence of chemicals in areas where these compounds have not been used. Environmental policy decisions can be based on either or both considerations depending on the aim of the regulatory program. In this chapter, definitions and methods for quantifying persistence and transport potential of organic chemicals are proposed which will assist in the development of sound regulatory frameworks.

  5. Conditioner for a helically transported electron beam

    SciTech Connect

    Wang, C.

    1992-05-01

    The kinetic theory is developed to investigate a conditioner for a helically imported electron beam. Linear expressions for axial velocity spread are derived. Numerical simulation is used to check the theoretical results and examine nonlinear aspects of the conditioning process. The results show that in the linear regime the action of the beam conditioner on a pulsed beam mainly depends on the phase at which the beam enters the conditioner and depends only slightly on the operating wavelength. In the nonlinear regime, however, the action of the conditioner strongly depends on the operating wavelength and only slightly upon the entrance phase. For a properly chosen operating wavelength, a little less than the electron`s relativistic cyclotron wavelength, the conditioner can decrease the axial velocity spread of a pulsed beam down to less than one-third of its initial value.

  6. Interactive design environment transportation channel of relativistic charged particle beams

    NASA Astrophysics Data System (ADS)

    Osadchuk, I. O.; Averyanov, G. P.; Budkin, V. A.

    2017-01-01

    Considered a modern implementation of a computer environment for the design of channels of transportation of high-energy charged particle beams. The environment includes a software package for the simulation of the dynamics of charged particles in the channel, operating means for changing parameters of the channel, the elements channel optimization and processing of the output characteristics of the beam with the graphical output the main output parameters.

  7. Coherent electron transport in a helical nanotube

    NASA Astrophysics Data System (ADS)

    Liang, Guo-Hua; Wang, Yong-Long; Du, Long; Jiang, Hua; Kang, Guang-Zhen; Zong, Hong-Shi

    2016-09-01

    The quantum dynamics of carriers bound to helical tube surfaces is investigated in a thin-layer quantization scheme. By numerically solving the open-boundary Schrödinger equation in curvilinear coordinates, geometric effect on the coherent transmission spectra is analysed in the case of single propagating mode as well as multimode. It is shown that, the coiling endows the helical nanotube with different transport properties from a bent cylindrical surface. Fano resonance appears as a purely geometric effect in the conductance, the corresponding energy of quasibound state is obviously influenced by the torsion and length of the nanotube. We also find new plateaus in the conductance. The transport of double-degenerate mode in this geometry is reminiscent of the Zeeman coupling between the magnetic field and spin angular momentum in quasi-one-dimensional structure.

  8. Neoclassical electron transport in tokamaks with neutral-beam injection

    SciTech Connect

    Helander, P.; Akers, R.J.

    2005-04-15

    The collisional interaction between neutral-beam ions and bulk plasma electrons leads to convective transport of particles and energy similar to the well-known Ware pinch. These transport fluxes are calculated, and it is found that the particle flux is outward when the neutral beams are in the same direction as the plasma current and inward otherwise, while the opposite holds for the electron heat transport. This effectively shifts the neutral-beam fueling profile approximately one fast-ion banana width outward during coinjection and inward during counterinjection, and could help to explain why very different plasma behavior is sometimes observed when the direction of the plasma current is reversed.

  9. Electronic transport and scattering times in tungsten-decorated graphene

    NASA Astrophysics Data System (ADS)

    Elias, Jamie A.; Henriksen, Erik A.

    2017-02-01

    The electronic transport properties of a monolayer graphene device have been studied before and after the deposition of a dilute coating of tungsten adatoms on the surface. For coverages up to 2.5% of a monolayer, we find tungsten adatoms simultaneously donate electrons to graphene and reduce the carrier mobility, impacting the zero- and finite-field transport properties. Two independent transport analyses suggest the adatoms lie nearly 1 nm above the surface. The presence of adatoms is also seen to impact the low-field magnetoresistance, altering the signatures of weak localization.

  10. Hetero-Interfaces For Extreme Electronic Environments

    DTIC Science & Technology

    2014-07-23

    the substrate, cation non-stoichiometry and formation of anti-s Electron gas, hetero-interface, ionic defects, surface, electronic reconstruction. U... channels that allow Al-cations to move from the interface to the surface. Such a motion would result in the decrease of the electrostatic potential that...there have not been any observation of such channels yet. In an Al-rich film, since Al can move into A-site, they can form anti-site defects. Thus the

  11. Secondary electron generation, emission and transport: Effects on spacecraft charging and NASCAP models

    NASA Technical Reports Server (NTRS)

    Katz, Ira; Mandell, Myron; Roche, James C.; Purvis, Carolyn

    1987-01-01

    Secondary electrons control a spacecraft's response to a plasma environment. To accurately simulate spacecraft charging, the NASA Charging Analyzer Program (NASCAP) has mathematical models of the generation, emission and transport of secondary electrons. The importance of each of the processes and the physical basis for each of the NASCAP models are discussed. Calculations are presented which show that the NASCAP formulations are in good agreement with both laboratory and space experiments.

  12. Transport of secondary electrons and reactive species in ion tracks

    NASA Astrophysics Data System (ADS)

    Surdutovich, Eugene; Solov'yov, Andrey V.

    2015-08-01

    The transport of reactive species brought about by ions traversing tissue-like medium is analysed analytically. Secondary electrons ejected by ions are capable of ionizing other molecules; the transport of these generations of electrons is studied using the random walk approximation until these electrons remain ballistic. Then, the distribution of solvated electrons produced as a result of interaction of low-energy electrons with water molecules is obtained. The radial distribution of energy loss by ions and secondary electrons to the medium yields the initial radial dose distribution, which can be used as initial conditions for the predicted shock waves. The formation, diffusion, and chemical evolution of hydroxyl radicals in liquid water are studied as well. COST Action Nano-IBCT: Nano-scale Processes Behind Ion-Beam Cancer Therapy.

  13. Catalytic photoinduced electron transport across a lipid bilayer mediated by a membrane-soluble electron relay.

    PubMed

    Limburg, B; Bouwman, E; Bonnet, S

    2015-12-14

    Unidirectional photocatalytic electron transfer from a hydrophilic electron donor encapsulated in the interior of a liposome, to a hydrophilic electron acceptor on the other side of the membrane, has been achieved using the simple membrane-soluble electron relay 1-methoxy-N-methylphenazinium (MMP(+)). The total amount of photoproduct (>140 nmol) exceeds the number of moles of MMP(+) present (125 nmol), thus showing that the transport of electrons is catalytic.

  14. Photon-assisted electron transport in graphene: Scattering theory analysis

    SciTech Connect

    Trauzettel, B.; Blanter, Ya. M.; Morpurgo, A. F.

    2007-01-15

    Photon-assisted electron transport in ballistic graphene is analyzed using scattering theory. We show that the presence of an ac signal (applied to a gate electrode in a region of the system) has interesting consequences on electron transport in graphene, where the low energy dynamics is described by the Dirac equation. In particular, such a setup describes a feasible way to probe energy dependent transmission in graphene. This is of substantial interest because the energy dependence of transmission in mesoscopic graphene is the basis of many peculiar transport phenomena proposed in the recent literature. Furthermore, we discuss the relevance of our analysis of ac transport in graphene to the observability of zitterbewegung of electrons that behave as relativistic particles (but with a lower effective speed of light)

  15. Student Performance in an Electronic Text Environment.

    ERIC Educational Resources Information Center

    Friedman, Edward A.; And Others

    1989-01-01

    Describes a project conducted at Stevens Institute of Technology to develop and test the applicability of full-text electronic databases and full-text retrieval technology for use in undergraduate humanities education. The creation of a machine-readable database on Galileo is described, student reactions are discussed, and further work is…

  16. Electronic Transport in Phosphorus-Doped Silicon Nanocrystal Networks

    NASA Astrophysics Data System (ADS)

    Stegner, A. R.; Pereira, R. N.; Klein, K.; Lechner, R.; Dietmueller, R.; Brandt, M. S.; Stutzmann, M.; Wiggers, H.

    2008-01-01

    We have investigated the role of doping and paramagnetic states on the electronic transport of networks assembled from freestanding Si nanocrystals (Si-NCs). Electrically detected magnetic resonance (EDMR) studies on Si-NCs films, which show a strong increase of conductivity with doping of individual Si-NCs, reveal that P donors and Si dangling bonds contribute to dark conductivity via spin-dependent hopping, whereas in photoconductivity, these states act as spin-dependent recombination centers of photogenerated electrons and holes. Comparison between EDMR and conventional electron paramagnetic resonance shows that different subsets of P-doped nanocrystals contribute to the different transport processes.

  17. Electronic transport in phosphorus-doped silicon nanocrystal networks.

    PubMed

    Stegner, A R; Pereira, R N; Klein, K; Lechner, R; Dietmueller, R; Brandt, M S; Stutzmann, M; Wiggers, H

    2008-01-18

    We have investigated the role of doping and paramagnetic states on the electronic transport of networks assembled from freestanding Si nanocrystals (Si-NCs). Electrically detected magnetic resonance (EDMR) studies on Si-NCs films, which show a strong increase of conductivity with doping of individual Si-NCs, reveal that P donors and Si dangling bonds contribute to dark conductivity via spin-dependent hopping, whereas in photoconductivity, these states act as spin-dependent recombination centers of photogenerated electrons and holes. Comparison between EDMR and conventional electron paramagnetic resonance shows that different subsets of P-doped nanocrystals contribute to the different transport processes.

  18. Electron transport through nuclear pasta in magnetized neutron stars

    NASA Astrophysics Data System (ADS)

    Yakovlev, D. G.

    2015-10-01

    We present a simple model for electron transport in a possible layer of exotic nuclear clusters (in the so-called nuclear pasta layer) between the crust and liquid core of a strongly magnetized neutron star. The electron transport there can be strongly anisotropic and gyrotropic. The anisotropy is produced by different electron effective collision frequencies along and across local symmetry axis in domains of exotic ordered nuclear clusters and by complicated effects of the magnetic field. We also calculate averaged kinetic coefficients in case local domains are freely oriented. Possible applications of the obtained results and open problems are outlined.

  19. Experiments on viscous transport in pure-electron plasmas

    NASA Astrophysics Data System (ADS)

    Kriesel, Jason M.; Driscoll, C. Fred

    1999-12-01

    Viscous transport in pure-electron plasmas is a rearrangement of particles due to like-particle interactions, eventually leading to a confined global thermal equilibrium state. The measured transport is observed to be proportional to the shear in the total (E×B+diamagnetic) fluid rotation of the plasma, for both hollow and monotonic rotation profiles. We determine the local kinematic viscosity, κ, from measurements of the local flux of electrons. The measured viscosity is 50-104 times larger than expected from classical transport due to short-range velocity-scattering collisions, but is within a factor of 10 of recent theories by O'Neil and Dubin of transport due to long-range drift collisions. The measured viscosity scales with magnetic field and plasma length roughly as κ∝B/L. This scaling suggests a finite-length transport enhancement caused by particles interacting multiple times as they bounce axially between the ends of the plasma.

  20. Treating electron transport in MCNP{sup trademark}

    SciTech Connect

    Hughes, H.G.

    1996-12-31

    The transport of electrons and other charged particles is fundamentally different from that of neutrons and photons. A neutron, in aluminum slowing down from 0.5 MeV to 0.0625 MeV will have about 30 collisions; a photon will have fewer than ten. An electron with the same energy loss will undergo 10{sup 5} individual interactions. This great increase in computational complexity makes a single- collision Monte Carlo approach to electron transport unfeasible for many situations of practical interest. Considerable theoretical work has been done to develop a variety of analytic and semi-analytic multiple-scattering theories for the transport of charged particles. The theories used in the algorithms in MCNP are the Goudsmit-Saunderson theory for angular deflections, the Landau an theory of energy-loss fluctuations, and the Blunck-Leisegang enhancements of the Landau theory. In order to follow an electron through a significant energy loss, it is necessary to break the electron`s path into many steps. These steps are chosen to be long enough to encompass many collisions (so that multiple-scattering theories are valid) but short enough that the mean energy loss in any one step is small (for the approximations in the multiple-scattering theories). The energy loss and angular deflection of the electron during each step can then be sampled from probability distributions based on the appropriate multiple- scattering theories. This subsumption of the effects of many individual collisions into single steps that are sampled probabilistically constitutes the ``condensed history`` Monte Carlo method. This method is exemplified in the ETRAN series of electron/photon transport codes. The ETRAN codes are also the basis for the Integrated TIGER Series, a system of general-purpose, application-oriented electron/photon transport codes. The electron physics in MCNP is similar to that of the Integrated TIGER Series.

  1. Electron transport in micro to nanoscale solid state networks

    NASA Astrophysics Data System (ADS)

    Fairbanks, Matthew Stetson

    This dissertation focuses on low-dimensional electron transport phenomena in devices ranging from semiconductor electron 'billiards' to semimetal atomic clusters to gold nanoparticles. In each material system, the goal of this research is to understand how carrier transport occurs when many elements act in concert. In the semiconductor electron billiards, magnetoconductance fluctuations, the result of electron quantum interference within the device, are used as a probe of electron transport through arrays of one, two, and three connected billiards. By combining two established analysis techniques, this research demonstrates a novel method for determining the quantum energy level spacing in each of the arrays. That information in turn shows the extent (and limits) of the phase-coherent electron wavefunction in each of the devices. The use of the following two material systems, the semimetal atomic clusters and the gold nanoparticles, is inspired by the electron billiard results. First, the output of the simple, rectangular electron billiards, the magnetoconductance fluctuations, is quite generally found to be fractal. This research addresses the question of what output one might expect from a device with manifestly fractal geometry by simulating the electrical response of fractal resistor networks and by outlining a method to implement such devices in fractal aggregates of semimetal atomic clusters. Second, in gold nanoparticle arrays, the number of array elements can increase by orders of magnitude over the billiard arrays, all with the potential to stay in a similar, phase-coherent transport regime. The last portion of this dissertation details the fabrication of these nanoparticle-based devices and their electrical characteristics, which exhibit strong evidence for electron transport in the Coulomb-blockade regime. A sketch for further 'off-blockade' experiments to realize magnetoconductance fluctuations, i.e. phase-coherent electron phenomena, is presented.

  2. Topological transport in Dirac electronic systems: A concise review

    NASA Astrophysics Data System (ADS)

    Song, Hua-Ding; Sheng, Dian; Wang, An-Qi; Li, Jin-Guang; Yu, Da-Peng; Liao, Zhi-Min

    2017-03-01

    Various novel physical properties have emerged in Dirac electronic systems, especially the topological characters protected by symmetry. Current studies on these systems have been greatly promoted by the intuitive concepts of Berry phase and Berry curvature, which provide precise definitions of the topological orders. In this topical review, transport properties of topological insulator (Bi2Se3), topological Dirac semimetal (Cd3As2) and topological insulator-graphene heterojunction are presented and discussed. Perspectives about transport properties of two-dimensional topological nontrivial systems, including topological edge transport, topological valley transport and topological Weyl semimetals, are provided.

  3. The integrated development of tools and environments for electronic design

    SciTech Connect

    Wagner, F.R.

    1996-12-31

    This paper discusses the relationships between the development of design tools and design environments for electronic circuits and systems. It is shown that the development of both the tools and the environment must be performed on an integrated way and depend on a design process to be supported. A methodology for the development of integrated and open design environments is shown. It considers different tool integration approaches and the selection of either environment-independent or dependent design tools.

  4. Electronic and Ionic Transport in Polymers

    DTIC Science & Technology

    1988-07-12

    containing electrolytes such as Bu4,NBF4 and LiBF4 to demonstrate the effect of ion size on charge transport. We show that, compared to polypyrrole, in the...activated molecular sieves prior to use. Tetrabutylammonium fluoroborate (TBABF4), lithium fluoroborate ( LiBF4 ), and tetraethyl- ammonium tosylate...0.1M ( LiBF4 ) is shown in S Figure 2 with the CV for polypyrrole (PP) in the same medium for comparison. The apparent , oscillations in the CV of the

  5. Conditioner for a helically transported electron beam

    SciTech Connect

    Wang, C.

    1992-05-01

    The kinetic theory is developed to investigate a conditioner for a helically imported electron beam. Linear expressions for axial velocity spread are derived. Numerical simulation is used to check the theoretical results and examine nonlinear aspects of the conditioning process. The results show that in the linear regime the action of the beam conditioner on a pulsed beam mainly depends on the phase at which the beam enters the conditioner and depends only slightly on the operating wavelength. In the nonlinear regime, however, the action of the conditioner strongly depends on the operating wavelength and only slightly upon the entrance phase. For a properly chosen operating wavelength, a little less than the electron's relativistic cyclotron wavelength, the conditioner can decrease the axial velocity spread of a pulsed beam down to less than one-third of its initial value.

  6. Monte Carlo simulations of electron transport in strongly attaching gases

    NASA Astrophysics Data System (ADS)

    Petrovic, Zoran; Miric, Jasmina; Simonovic, Ilija; Bosnjakovic, Danko; Dujko, Sasa

    2016-09-01

    Extensive loss of electrons in strongly attaching gases imposes significant difficulties in Monte Carlo simulations at low electric field strengths. In order to compensate for such losses, some kind of rescaling procedures must be used. In this work, we discuss two rescaling procedures for Monte Carlo simulations of electron transport in strongly attaching gases: (1) discrete rescaling, and (2) continuous rescaling. The discrete rescaling procedure is based on duplication of electrons randomly chosen from the remaining swarm at certain discrete time steps. The continuous rescaling procedure employs a dynamically defined fictitious ionization process with the constant collision frequency chosen to be equal to the attachment collision frequency. These procedures should not in any way modify the distribution function. Monte Carlo calculations of transport coefficients for electrons in SF6 and CF3I are performed in a wide range of electric field strengths. However, special emphasis is placed upon the analysis of transport phenomena in the limit of lower electric fields where the transport properties are strongly affected by electron attachment. Two important phenomena arise: (1) the reduction of the mean energy with increasing E/N for electrons in SF6, and (2) the occurrence of negative differential conductivity in the bulk drift velocity of electrons in both SF6 and CF3I.

  7. A model environment for outer zone electrons

    NASA Technical Reports Server (NTRS)

    Singley, G. W.; Vette, J. I.

    1972-01-01

    A brief morphology of outer zone electrons is given to illustrate the nature of the phenomena that we are attempting to model. This is followed by a discussion of the data processing that was done with the various data received from the experimenters before incorporating it into the data base from which this model was ultimately derived. The details of the derivation are given, and several comparisons of the final model with the various experimental measurements are presented.

  8. Non-equilibrium normal and critical transport of electrons in strontium-doped bismuthate cuprates

    NASA Astrophysics Data System (ADS)

    Kwang-Hua, Chu Rainer

    2014-05-01

    Critical dynamical transitional phases of electronic liquids driven by an initial electric field in a microscopic confined environment at low temperature regime could occur after we investigated by adopting the verified theory of absolute reactions. The critical temperatures related to the nearly frictionless transport of many condensed electrons might be directly relevant to the dynamical transition at low-temperature regime in amorphous materials, say (Bi2-xSrx)2CuO6, after selecting specific activation energies and activation volumes. We also address the normal-state high-temperature transport issue.

  9. Transport and Non-Invasive Position Detection of Electron Beams from Laser-Plasma Accelerators

    SciTech Connect

    Osterhoff, Jens; Sokollik, Thomas; Nakamura, Kei; Bakeman, Michael; Weingartner, R; Gonsalves, Anthony; Shiraishi, Satomi; Lin, Chen; vanTilborg, Jeroen; Geddes, Cameron; Schroeder, Carl; Esarey, Eric; Toth, Csaba; DeSantis, Stefano; Byrd, John; Gruner, F; Leemans, Wim

    2011-07-20

    The controlled imaging and transport of ultra-relativistic electrons from laser-plasma accelerators is of crucial importance to further use of these beams, e.g. in high peak-brightness light sources. We present our plans to realize beam transport with miniature permanent quadrupole magnets from the electron source through our THUNDER undulator. Simulation results demonstrate the importance of beam imaging by investigating the generated XUV-photon flux. In addition, first experimental findings of utilizing cavity-based monitors for non-invasive beam-position measurements in a noisy electromagnetic laser-plasma environment are discussed.

  10. Introduction to special section on Colloid Transport in Subsurface Environments

    NASA Astrophysics Data System (ADS)

    Saiers, James E.; Ryan, Joseph N.

    2006-12-01

    The Water Resources Research special section on Colloid Transport in Subsurface Environments presents new knowledge that is critical to solving problems related to groundwater pollution by microbial pathogens and hazardous chemicals. This introduction to the special section surveys fourteen manuscripts that advance current understanding of the transport of biocolloids (e.g., bacteria, viruses, and protozoa), mineral colloids, and colloid-associated contaminants in the vadose zone and in groundwater. These papers present new techniques for elucidating mechanisms that govern colloid mobility, propose mathematical models appropriate for quantifying colloid and colloid-associated contaminant transport, and report pore-scale and column-scale observations requisite for evaluating these models. Together, the papers of this special section illuminate the complexity of the colloid transport problem and describe progress toward understanding this complexity.

  11. Electronic Structure and Transport in Magnetic Multilayers

    SciTech Connect

    2008-02-18

    ORNL assisted Seagate Recording Heads Operations in the development of CIPS pin Valves for application as read sensors in hard disk drives. Personnel at ORNL were W. H. Butler and Xiaoguang Zhang. Dr. Olle Heinonen from Seagate RHO also participated. ORNL provided codes and materials parameters that were used by Seagate to model CIP GMR in their heads. The objectives were to: (1) develop a linearized Boltzmann transport code for describing CIP GMR based on realistic models of the band structure and interfaces in materials in CIP spin valves in disk drive heads; (2) calculate the materials parameters needed as inputs to the Boltzmann code; and (3) transfer the technology to Seagate Recording Heads.

  12. Pyradinodithiazole: An Electron-Accepting Monomer Unit for Hole-Transporting and Electron-Transporting Conjugated Copolymers.

    PubMed

    Ie, Yutaka; Sasada, Shohei; Karakawa, Makoto; Aso, Yoshio

    2015-09-18

    Pyradinodithiazole (PDTz) was designed as a new electron-accepting unit. The physical property measurements indicated that the PDTz unit has stronger electron-accepting characteristics than thiazolothiazole and benzodithiazole. A donor-acceptor copolymer containing PDTz as an acceptor unit was synthesized for hole-transporting semiconductors in organic photovoltaics (OPV). Furthermore, an acceptor-acceptor copolymer containing PDTz has also been developed for electron-transporting OPV materials. These copolymer-based blend films showed expected photovoltaic characteristics in individual OPV devices.

  13. Electron transport and light-harvesting switches in cyanobacteria

    PubMed Central

    Mullineaux, Conrad W.

    2014-01-01

    Cyanobacteria possess multiple mechanisms for regulating the pathways of photosynthetic and respiratory electron transport. Electron transport may be regulated indirectly by controlling the transfer of excitation energy from the light-harvesting complexes, or it may be more directly regulated by controlling the stoichiometry, localization, and interactions of photosynthetic and respiratory electron transport complexes. Regulation of the extent of linear vs. cyclic electron transport is particularly important for controlling the redox balance of the cell. This review discusses what is known of the regulatory mechanisms and the timescales on which they occur, with particular regard to the structural reorganization needed and the constraints imposed by the limited mobility of membrane-integral proteins in the crowded thylakoid membrane. Switching mechanisms requiring substantial movement of integral thylakoid membrane proteins occur on slower timescales than those that require the movement only of cytoplasmic or extrinsic membrane proteins. This difference is probably due to the restricted diffusion of membrane-integral proteins. Multiple switching mechanisms may be needed to regulate electron transport on different timescales. PMID:24478787

  14. Electron transport and light-harvesting switches in cyanobacteria.

    PubMed

    Mullineaux, Conrad W

    2014-01-01

    Cyanobacteria possess multiple mechanisms for regulating the pathways of photosynthetic and respiratory electron transport. Electron transport may be regulated indirectly by controlling the transfer of excitation energy from the light-harvesting complexes, or it may be more directly regulated by controlling the stoichiometry, localization, and interactions of photosynthetic and respiratory electron transport complexes. Regulation of the extent of linear vs. cyclic electron transport is particularly important for controlling the redox balance of the cell. This review discusses what is known of the regulatory mechanisms and the timescales on which they occur, with particular regard to the structural reorganization needed and the constraints imposed by the limited mobility of membrane-integral proteins in the crowded thylakoid membrane. Switching mechanisms requiring substantial movement of integral thylakoid membrane proteins occur on slower timescales than those that require the movement only of cytoplasmic or extrinsic membrane proteins. This difference is probably due to the restricted diffusion of membrane-integral proteins. Multiple switching mechanisms may be needed to regulate electron transport on different timescales.

  15. Evidence for global electron transportation into the jovian inner magnetosphere.

    PubMed

    Yoshioka, K; Murakami, G; Yamazaki, A; Tsuchiya, F; Kimura, T; Kagitani, M; Sakanoi, T; Uemizu, K; Kasaba, Y; Yoshikawa, I; Fujimoto, M

    2014-09-26

    Jupiter's magnetosphere is a strong particle accelerator that contains ultrarelativistic electrons in its inner part. They are thought to be accelerated by whistler-mode waves excited by anisotropic hot electrons (>10 kiloelectron volts) injected from the outer magnetosphere. However, electron transportation in the inner magnetosphere is not well understood. By analyzing the extreme ultraviolet line emission from the inner magnetosphere, we show evidence for global inward transport of flux tubes containing hot plasma. High-spectral-resolution scanning observations of the Io plasma torus in the inner magnetosphere enable us to generate radial profiles of the hot electron fraction. It gradually decreases with decreasing radial distance, despite the short collisional time scale that should thermalize them rapidly. This indicates a fast and continuous resupply of hot electrons responsible for exciting the whistler-mode waves.

  16. Evidence for global electron transportation into the jovian inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Yoshioka, K.; Murakami, G.; Yamazaki, A.; Tsuchiya, F.; Kimura, T.; Kagitani, M.; Sakanoi, T.; Uemizu, K.; Kasaba, Y.; Yoshikawa, I.; Fujimoto, M.

    2014-09-01

    Jupiter’s magnetosphere is a strong particle accelerator that contains ultrarelativistic electrons in its inner part. They are thought to be accelerated by whistler-mode waves excited by anisotropic hot electrons (>10 kiloelectron volts) injected from the outer magnetosphere. However, electron transportation in the inner magnetosphere is not well understood. By analyzing the extreme ultraviolet line emission from the inner magnetosphere, we show evidence for global inward transport of flux tubes containing hot plasma. High-spectral-resolution scanning observations of the Io plasma torus in the inner magnetosphere enable us to generate radial profiles of the hot electron fraction. It gradually decreases with decreasing radial distance, despite the short collisional time scale that should thermalize them rapidly. This indicates a fast and continuous resupply of hot electrons responsible for exciting the whistler-mode waves.

  17. Unification of trap-limited electron transport in semiconducting polymers.

    PubMed

    Nicolai, H T; Kuik, M; Wetzelaer, G A H; de Boer, B; Campbell, C; Risko, C; Brédas, J L; Blom, P W M

    2012-10-01

    Electron transport in semiconducting polymers is usually inferior to hole transport, which is ascribed to charge trapping on isolated defect sites situated within the energy bandgap. However, a general understanding of the origin of these omnipresent charge traps, as well as their energetic position, distribution and concentration, is lacking. Here we investigate electron transport in a wide range of semiconducting polymers by current-voltage measurements of single-carrier devices. We observe for this materials class that electron transport is limited by traps that exhibit a gaussian energy distribution in the bandgap. Remarkably, the electron-trap distribution is identical for all polymers considered: the number of traps amounts to 3 × 10(23) traps per m(3) centred at an energy of ~3.6 eV below the vacuum level, with a typical distribution width of ~0.1 eV. This indicates that the electron traps have a common origin that, we suggest, is most likely related to hydrated oxygen complexes. A consequence of this finding is that the trap-limited electron current can be predicted for any polymer.

  18. 76 FR 50312 - Surface Transportation Environment and Planning Cooperative Research Program (STEP)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-12

    ... Federal Highway Administration Surface Transportation Environment and Planning Cooperative Research...-LU) established the Surface Transportation Environment and Planning Cooperative Research Program... research on issues related to planning, environment, and realty will be included in future surface...

  19. Advanced Engineering Environments for Space Transportation System Development

    NASA Technical Reports Server (NTRS)

    Thomas, L. Dale; Smith, Charles A.; Beveridge, James

    2000-01-01

    There are significant challenges facing today's launch vehicle industry. Global competition, more complex products, geographically-distributed design teams, demands for lower cost, higher reliability and safer vehicles, and the need to incorporate the latest technologies quicker, all face the developer of a space transportation system. Within NASA, multiple technology development and demonstration projects are underway toward the objectives of safe, reliable, and affordable access to space. New information technologies offer promising opportunities to develop advanced engineering environments to meet these challenges. Significant advances in the state-of-the-art of aerospace engineering practice are envisioned in the areas of engineering design and analytical tools, cost and risk tools, collaborative engineering, and high-fidelity simulations early in the development cycle. At the Marshall Space Flight Center, work has begun on development of an advanced engineering environment specifically to support the design, modeling, and analysis of space transportation systems. This paper will give an overview of the challenges of developing space transportation systems in today's environment and subsequently discuss the advanced engineering environment and its anticipated benefits.

  20. Effect of dephasing on DNA sequencing via transverse electronic transport

    SciTech Connect

    Zwolak, Michael; Krems, Matt; Pershin, Yuriy V; Di Ventra, Massimiliano

    2009-01-01

    We study theoretically the effects of dephasing on DNA sequencing in a nanopore via transverse electronic transport. To do this, we couple classical molecular dynamics simulations with transport calculations using scattering theory. Previous studies, which did not include dephasing, have shown that by measuring the transverse current of a particular base multiple times, one can get distributions of currents for each base that are distinguishable. We introduce a dephasing parameter into transport calculations to simulate the effects of the ions and other fluctuations. These effects lower the overall magnitude of the current, but have little effect on the current distributions themselves. The results of this work further implicate that distinguishing DNA bases via transverse electronic transport has potential as a sequencing tool.

  1. Mitochondrial ROS Produced via Reverse Electron Transport Extend Animal Lifespan.

    PubMed

    Scialò, Filippo; Sriram, Ashwin; Fernández-Ayala, Daniel; Gubina, Nina; Lõhmus, Madis; Nelson, Glyn; Logan, Angela; Cooper, Helen M; Navas, Plácido; Enríquez, Jose Antonio; Murphy, Michael P; Sanz, Alberto

    2016-04-12

    Increased production of reactive oxygen species (ROS) has long been considered a cause of aging. However, recent studies have implicated ROS as essential secondary messengers. Here we show that the site of ROS production significantly contributes to their apparent dual nature. We report that ROS increase with age as mitochondrial function deteriorates. However, we also demonstrate that increasing ROS production specifically through respiratory complex I reverse electron transport extends Drosophila lifespan. Reverse electron transport rescued pathogenesis induced by severe oxidative stress, highlighting the importance of the site of ROS production in signaling. Furthermore, preventing ubiquinone reduction, through knockdown of PINK1, shortens lifespan and accelerates aging; phenotypes that are rescued by increasing reverse electron transport. These results illustrate that the source of a ROS signal is vital in determining its effects on cellular physiology and establish that manipulation of ubiquinone redox state is a valid strategy to delay aging.

  2. Mitochondrial ROS Produced via Reverse Electron Transport Extend Animal Lifespan

    PubMed Central

    Scialò, Filippo; Sriram, Ashwin; Fernández-Ayala, Daniel; Gubina, Nina; Lõhmus, Madis; Nelson, Glyn; Logan, Angela; Cooper, Helen M.; Navas, Plácido; Enríquez, Jose Antonio; Murphy, Michael P.; Sanz, Alberto

    2016-01-01

    Summary Increased production of reactive oxygen species (ROS) has long been considered a cause of aging. However, recent studies have implicated ROS as essential secondary messengers. Here we show that the site of ROS production significantly contributes to their apparent dual nature. We report that ROS increase with age as mitochondrial function deteriorates. However, we also demonstrate that increasing ROS production specifically through respiratory complex I reverse electron transport extends Drosophila lifespan. Reverse electron transport rescued pathogenesis induced by severe oxidative stress, highlighting the importance of the site of ROS production in signaling. Furthermore, preventing ubiquinone reduction, through knockdown of PINK1, shortens lifespan and accelerates aging; phenotypes that are rescued by increasing reverse electron transport. These results illustrate that the source of a ROS signal is vital in determining its effects on cellular physiology and establish that manipulation of ubiquinone redox state is a valid strategy to delay aging. PMID:27076081

  3. Cyclic electron transport in C3 plants: fact or artefact?

    PubMed

    Johnson, Giles N

    2005-01-01

    The phenomenon of cyclic electron transport was first characterized in higher plant chloroplasts 50 years ago, yet there is still a debate about whether or not this is a physiological process. The recent isolation of mutants that appear to lack cyclic electron transport, as well as new data providing functional evidence for its occurrence, support the notion that this pathway plays an important role in plant responses to stress, providing a pH gradient across the thylakoid membrane to trigger non-photochemical quenching of chlorophyll fluorescence. At present, little is known about the regulation of cyclic electron transport, but it is possible that this is activated in response to a low redox potential in the chloroplast stroma.

  4. Transport of Iodine Species in the Terrestrial Environment

    NASA Astrophysics Data System (ADS)

    Hu, Q.; Moran, J.; Zhao, P.

    2003-12-01

    The fate and transport of iodine in the environment is of interest because of the large production and release of 129I from anthropogenic sources. 129I has a long half-life (1.57 x 107 years) and exhibits complex geochemical behavior. The main source of 129I in the environment is from nuclear fuel reprocessing facilities; about 2,600 kg from facilities in England and France. During 1944-1972, the Hanford Site in Washington state released about 260 kg 129I. Iodine has a unique and complex chemistry in the environment, and its fate and transport in aqueous environments is dictated by its chemical speciation. In reducing environments, aqueous iodine usually occurs as the highly mobile iodide anion (I-). Under more oxidizing conditions, iodine may be present as the more reactive iodate anion (IO3-), which could lead to retarded transport through interaction with clays and organic matter. Co-existing iodine species (I-, IO3-, I2, and organoiodine compounds), in different proportions, has been reported in various terrestrial environments. However, there are conflicting reports regarding the environmental behavior of the different types of inorganic iodine and few publications on organic iodine compounds. This work examines the sorption and transport behavior of both inorganic and organic iodine species in geological samples from several complexes of the U.S. Department of Energy, where transport of radionuclides, including 129I, may occur. Experiments on soils and sediments from the Savannah River Site in South Carolina, Oak Ridge Site in Tennessee, Hanford Site in Washington, Livermore Site 300 in California, and a surface soil from Santa Fe in New Mexico near Los Alamos were carried out. Samples from Savannah River Site and Livermore Site 300 are available from different depths. In addition, a surface soil of Wisconsin with a high amount of organic matter is utilized. This wide variety of sample types provides opportunities to examine the influence of organic matter

  5. Changes in mitochondrial electron transport chain activity during insect metamorphosis.

    PubMed

    Chamberlin, M E

    2007-02-01

    The midgut of the tobacco hornworm (Manduca sexta) is a highly aerobic tissue that is destroyed by programmed cell death during larval-pupal metamorphosis. The death of the epithelium begins after commitment to pupation, and the oxygen consumption of isolated midgut mitochondria decreases soon after commitment. To assess the role of the electron transport chain in this decline in mitochondrial function, the maximal activities of complexes I-IV of the respiratory chain were measured in isolated midgut mitochondria. Whereas there were no developmental changes in the activity of complex I or III, activities of complexes II and IV [cytochrome c oxidase (COX)] were higher in mitochondria from precommitment than postcommitment larvae. This finding is consistent with a higher rate of succinate oxidation in mitochondria isolated from precommitment larvae and reveals that the metamorphic decline in mitochondrial respiration is due to the targeted destruction or inactivation of specific sites within the mitochondria, rather than the indiscriminate destruction of the organelles. The COX turnover number (e- x s(-1) x cytochrome aa3(-1)) was greater for the enzyme from precommitment than postcommitment larvae, indicating a change in the enzyme structure and/or its lipid environment during the early stages of metamorphosis. The turnover number of COX in the intact mitochondria (in organello COX) was also lower in postcommitment larvae. In addition to changes in the protein or membrane phospholipids, the metamorphic decline in this rate constant may be a result of the observed loss of endogenous cytochrome c.

  6. Progress in Simulating Turbulent Electron Thermal Transport in NSTX

    SciTech Connect

    Guttenfelder, Walter; Kaye, S. M.; Ren, Y.; Bell, R. E.; Hammett, G. W.; LeBlanc, B. P.; Mikkelsen, D. R.; Peterson, J. L.; Nevins, W. M.; Candy, J.; Yuh, H.

    2013-07-17

    Nonlinear simulations based on multiple NSTX discharge scenarios have progressed to help differentiate unique instability mechanisms and to validate with experimental turbulence and transport data. First nonlinear gyrokinetic simulations of microtearing (MT) turbulence in a high-beta NSTX H-mode discharge predict experimental levels of electron thermal transport that are dominated by magnetic flutter and increase with collisionality, roughly consistent with energy confinement times in dimensionless collisionality scaling experiments. Electron temperature gradient (ETG) simulations predict significant electron thermal transport in some low and high beta discharges when ion scales are suppressed by E x B shear. Although the predicted transport in H-modes is insensitive to variation in collisionality (inconsistent with confinement scaling), it is sensitive to variations in other parameters, particularly density gradient stabilization. In reversed shear (RS) Lmode discharges that exhibit electron internal transport barriers, ETG transport has also been shown to be suppressed nonlinearly by strong negative magnetic shear, s<<0. In many high beta plasmas, instabilities which exhibit a stiff beta dependence characteristic of kinetic ballooning modes (KBM) are sometimes found in the core region. However, they do not have a distinct finite beta threshold, instead transitioning gradually to a trapped electron mode (TEM) as beta is reduced to zero. Nonlinear simulations of this "hybrid" TEM/KBM predict significant transport in all channels, with substantial contributions from compressional magnetic perturbations. As multiple instabilities are often unstable simultaneously in the same plasma discharge, even on the same flux surface, unique parametric dependencies are discussed which may be useful for distinguishing the different mechanisms experimentally.

  7. Radiation-Hardened Electronics for Space Environments (RHESE)

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Adams, James H.; Patrick, Marshall C.; Johnson, Michael; Cressler, John D.

    2008-01-01

    This conference poster explores NASA's Radiation-Hardened Electronics for Space Environments project. This project aims to advance the state of the art in high performance, radiation-hardened electronics that enable the long-term, reliable operation of a spacecraft in extreme radiation and temperature of space and the lunar surface.

  8. Coherently driven, ultrafast electron-phonon dynamics in transport junctions

    SciTech Connect

    Szekely, Joshua E.; Seideman, Tamar

    2014-07-28

    Although the vast majority of studies of transport via molecular-scale heterojunctions have been conducted in the (static) energy domain, experiments are currently beginning to apply time domain approaches to the nanoscale transport problem, combining spatial with temporal resolution. It is thus an opportune time for theory to develop models to explore both new phenomena in, and new potential applications of, time-domain, coherently driven molecular electronics. In this work, we study the interaction of a molecular phonon with an electronic wavepacket transmitted via a conductance junction within a time-domain model that treats the electron and phonon on equal footing and spans the weak to strong electron-phonon coupling strengths. We explore interference between two coherent energy pathways in the electronic subspace, thus complementing previous studies of coherent phenomena in conduction junctions, where the stationary framework was used to study interference between spatial pathways. Our model provides new insights into phase decoherence and population relaxation within the electronic subspace, which have been conventionally treated by density matrix approaches that often rely on phenomenological parameters. Although the specific case of a transport junction is explored, our results are general, applying also to other instances of coupled electron-phonon systems.

  9. Electron cross-sections and transport in liquids and biomolecules

    NASA Astrophysics Data System (ADS)

    White, Ronald; Casey, M.; Cocks, D.; Konvalov, D.; Brunger, M. J.; Garcia, G.; Petrovic, Z.; McEachran, R.; Buckman, S. J.; de Urquijo, J.

    2016-09-01

    Modelling of electron induced processes in plasma medicine and radiation damage is reliant on accurate self-consistent sets of cross-sections for electrons in tissue. These cross-sections (and associated transport theory) must accurately account not only the electron-biomolecule interactions but also for the soft-condensed nature of tissue. In this presentation, we report on recent swarm experiments for electrons in gaseous water and tetrahydrofuran using the pulsed-Townsend experiment, and the associated development of self-consistent cross-section sets that arise from them. We also report on the necessary modifications to gas-phase cross-sections required to accurately treat electron transport in liquids. These modifications involve the treatment of coherent scattering and screening of the electron interaction potential as well as the development of a new transport theory to accommodate these cross-sections. The accuracy of the ab-initio cross-sections is highlighted through comparison of theory and experiment for electrons in liquid argon and xenon.

  10. Dissipative transport of thermalized electrons through a nanodevice

    NASA Astrophysics Data System (ADS)

    Wołoszyn, M.; Spisak, B. J.

    2017-08-01

    An equilibrium distribution function which corresponds to thermalization of electrons in contacts due to scattering processes is introduced for the purpose of reformulation of the inflow boundary conditions for the Wigner kinetic equation. The importance of the proposed concept for more realistic descriptions of transport phenomena in nanodevices is illustrated by determination of characteristics of the nanowire in cases of dissipative and dissipationless states of its active region. Quantitative results show how transport characteristics of the nanodevice are modified by the contacts.

  11. Collective microdynamics and noise suppression in dispersive electron beam transport

    SciTech Connect

    Gover, Avraham; Dyunin, Egor; Duchovni, Tamir; Nause, Ariel

    2011-12-15

    A general formulation is presented for deep collective interaction micro-dynamics in dispersive e-beam transport. In the regime of transversely coherent interaction, the formulation is applicable to both coherent and random temporal modulation of the electron beam. We demonstrate its use for determining the conditions for suppressing beam current noise below the classical shot-noise level by means of transport through a dispersive section with a small momentum compaction parameter.

  12. Quantum Transport in Solids: Two-Electron Processes.

    DTIC Science & Technology

    1995-07-01

    The central objective of this research program has been to study theoretically the underlying principles of quantum transport in solids. The area of...research investigated has emphasized the understanding of two electron processes in quantum transport . The problems have been treated analytically to...the extent possible through the use of dynamical localized Wannier functions. These results have been and are being incorporated in a full quantum

  13. Quantum Transport in Solids: Two-Electron Processes.

    DTIC Science & Technology

    1995-06-01

    The central objective of this research program has been to study theoretically the underlying principles of quantum transport in solids. The area of...research investigated has emphasized the understanding of two electron processes in quantum transport . The problems have been treated analytically to...the extent possible through the use of dynamical localized Wannier functions. These results have been and are being incorporated in a full quantum

  14. Simulation of electron transport in quantum well devices

    NASA Technical Reports Server (NTRS)

    Miller, D. R.; Gullapalli, K. K.; Reddy, V. R.; Neikirk, D. P.

    1992-01-01

    Double barrier resonant tunneling diodes (DBRTD) have received much attention as possible terahertz devices. Despite impressive experimental results, the specifics of the device physics (i.e., how the electrons propagate through the structure) are only qualitatively understood. Therefore, better transport models are warranted if this technology is to mature. In this paper, the Lattice Wigner function is used to explain the important transport issues associated with DBRTD device behavior.

  15. Best Practices Experiences: Successful Use of Electronic Learning Environments.

    ERIC Educational Resources Information Center

    de Boer, W. F.; Fisser, P. H. G.

    Two popular learning environments, TeleTOP and Blackboard, are implemented for specific educational contexts in many universities and other institutions. The goal is to increase the use of information and communication technology (ICT) in education, particularly network technology or Web-based systems. These electronic learning environments do not…

  16. Ballistic electron transport in structured suspended semiconductor membranes

    SciTech Connect

    Pogosov, A. G.; Budantsev, M. V.; Zhdanov, E. Yu.; Pokhabov, D. A.

    2013-12-04

    We study ballistic electron transport in freely suspended AlAs/GaAs microstructures containing a high mobility two-dimensional electron gas with square lattice of antidots. We found that the magnetoresistance of the samples demonstrates commensurability oscillations both for the case of non-suspended and suspended devices. The temperature dependence of the commensurability oscillations is similar for both cases. However, the critical dc current, that suppresses these oscillations, in suspended samples is three times lower than in non-suspended ones. The observed phenomenon can be explained by peculiarities of the heat transport in membranes.

  17. Electronic structure and thermoelectric transport of black phosphorus

    NASA Astrophysics Data System (ADS)

    Craco, L.; Pereira, T. A. da Silva; Leoni, S.

    2017-08-01

    We investigate anisotropic electronic structure and thermal transport properties of bulk black phosphorus (BP). Using density functional dynamical mean-field theory we first derive a correlation-induced electronic reconstruction, showing band-selective Kondoesque physics in this elemental p -band material. The resulting correlated picture is expected to shed light onto the temperature and doping dependent evolution of resistivity, Seebeck coefficient, and thermal conductivity, as seen in experiments on bulk single crystal BP. Therein, large anisotropic particle-hole excitations are key to consistently understand thermoelectric transport responses of pure and doped BP.

  18. Contactless electronic transport in a bio-molecular junction

    SciTech Connect

    Hossain, Faruque M. Al-Dirini, Feras; Skafidas, Efstratios

    2014-07-28

    Molecular electronics hold promise for next generation ultra-low power, nano-scale integrated electronics. The main challenge in molecular electronics is to make a reliable interface between molecules and metal electrodes. Interfacing metals and molecules detrimentally affects the characteristics of nano-scale molecular electronic devices. It is therefore essential to investigate alternative arrangements such as contact-less tunneling gaps wherever such configurations are feasible. We conduct ab initio density functional theory and non-equilibrium Green's functions calculations to investigate the transport properties of a biocompatible glycine molecular junction. By analyzing the localized molecular orbital energy distributions and transmission probabilities in the transport-gap, we find a glycine molecule confined between two gold electrodes, without making a contact, is energetically stable and possesses high tunneling current resembling an excellent ohmic-like interface.

  19. Electronic transport in benzodifuran single-molecule transistors.

    PubMed

    Xiang, An; Li, Hui; Chen, Songjie; Liu, Shi-Xia; Decurtins, Silvio; Bai, Meilin; Hou, Shimin; Liao, Jianhui

    2015-05-07

    Benzodifuran (BDF) single-molecule transistors have been fabricated in electromigration break junctions for electronic measurements. The inelastic electron tunneling spectrum validates that the BDF molecule is the pathway of charge transport. The gating effect is analyzed in the framework of a single-level tunneling model combined with transition voltage spectroscopy (TVS). The analysis reveals that the highest occupied molecular orbital (HOMO) of the thiol-terminated BDF molecule dominates the charge transport through Au-BDF-Au junctions. Moreover, the energy shift of the HOMO caused by the gate voltage is the main reason for conductance modulation. In contrast, the electronic coupling between the BDF molecule and the gold electrodes, which significantly affects the low-bias junction conductance, is only influenced slightly by the applied gate voltage. These findings will help in the design of future molecular electronic devices.

  20. Electron Beam Freeform Fabrication in the Space Environment

    NASA Technical Reports Server (NTRS)

    Hafley, Robert A.; Taminger, Karen M. B.; Bird, R. Keith

    2007-01-01

    The influence of reduced gravitational forces (in space and on the lunar or Martian surfaces) on manufacturing processes must be understood for effective fabrication and repair of structures and replacement parts during long duration space missions. The electron beam freeform fabrication (EBF3) process uses an electron beam and wire to fabricate metallic structures. The process efficiencies of the electron beam and the solid wire feedstock make the EBF3 process attractive for use in-space. This paper will describe the suitability of the EBF3 process in the space environment and will highlight preliminary testing of the EBF3 process in a zero-gravity environment.

  1. Transport properties of anyons in random topological environments

    NASA Astrophysics Data System (ADS)

    Zatloukal, V.; Lehman, L.; Singh, S.; Pachos, J. K.; Brennen, G. K.

    2014-10-01

    The quasi-one-dimensional transport of Abelian and non-Abelian anyons is studied in the presence of a random topological background. In particular, we consider the quantum walk of an anyon that braids around islands of randomly filled static anyons of the same type. Two distinct behaviors are identified. We analytically demonstrate that all types of Abelian anyons localize purely due to the statistical phases induced by their random anyonic environment. In contrast, we numerically show that non-Abelian Ising anyons do not localize. This is due to their entanglement with the anyonic environment, which effectively induces dephasing. Our study demonstrates that localization properties strongly depend on nonlocal topological interactions, and it provides a clear distinction in the transport properties of Abelian and non-Abelian anyons.

  2. An orbital rule for electron transport in molecules.

    PubMed

    Yoshizawa, Kazunari

    2012-09-18

    The transfer of electrons in molecules and solids is an essential process both in biological systems and in electronic devices. Devices that take advantage of the unique electronic properties of a single molecule have attracted much attention, and applications of these devices include molecular wire, molecular memory, and molecular diodes. The so-called Landauer formula with Green's function techniques provides a basis for theoretical calculations of coherent electron transport in metal-molecule-metal junctions. We have developed a chemical way of thinking about electron transport in molecules in terms of frontier orbital theory. The phase and amplitude of the HOMO and LUMO of π-conjugated molecules determine the essential properties of their electron transport. By considering a close relationship between Green's function and the molecular orbital, we derived an orbital rule that would help our chemical understanding of the phenomenon. First, the sign of the product of the orbital coefficients at sites r and s in the HOMO should be different from the sign of the product of the orbital coefficients at sites r and s in the LUMO. Second, sites r and s in which the amplitude of the HOMO and LUMO is large should be connected. The derived rule allows us to predict essential electron transport properties, which significantly depend on the route of connection between a molecule and electrodes. Qualitative analyses of the site-dependent electron transport in naphthalene (as shown in the graphics) demonstrate that connections 1-4, 1-5, 2-3, and 2-6 are symmetry-allowed for electron transmission, while connections 1-8 and 2-7 are symmetry-forbidden. On the basis of orbital interaction analysis, we have extended this rule to metal-molecule-metal junctions of dithiol derivatives in which two gold electrodes have direct contacts with a molecule through two Au-S bonds. Recently we confirmed these theoretical predictions experimentally by using nanofabricated mechanically

  3. Study of Electron Transport and Amplification in Diamond

    SciTech Connect

    Muller, Erik M.; Ben-Zvi, Ilan

    2013-03-31

    As a successful completion of this award, my group has demonstrated world-leading electron gain from diamond for use in a diamond-amplified photocathode. Also, using high-resolution photoemission measurements we were able to uncover exciting new physics of the electron emission mechanisms from hydrogen terminated diamond. Our work, through the continued support of HEP, has resulted in a greater understanding of the diamond material science, including current limits, charge transport modeling, and spatial uniformity.

  4. Origin of electronic transport of lithium phthalocyanine iodine crystal

    SciTech Connect

    Koike, Noritake; Oda, Masato; Shinozuka, Yuzo

    2013-12-04

    The electronic structures of Lithium Phthalocyanine Iodine are investigated using density functional theory. Comparing the band structures of several model crystals, the metallic conductivity of highly doped LiPcI{sub x} can be explained by the band of doped iodine. These results reveal that there is a new mechanism for electronic transport of doped organic semiconductors that the dopant band plays the main role.

  5. Electron transport in EBT in the low collision frequency limit

    SciTech Connect

    Hastings, D.E.

    1984-06-01

    A variational principle formulation is used to calculate the electron neoclassical transport coefficients in a bumpy torus for the low collisionality regime. The electron radial drift is calculated as a function of the plasma position and the poloidal electric field which is determined self-consistently. A bounce-averaged differential collision operator is used and the results are compared to previous treatments using a BGK operator.

  6. Non equilibrium electronic transport in multilayered nanostructures

    NASA Astrophysics Data System (ADS)

    Cruz-Rojas, Jesus

    Recent advances in strongly correlated materials have produced systems with novel and interesting properties like high Tc superconductors, Mott insulators and others. These novel properties have sparked an interest in industry as well as in academia as new devices are being developed. One such kind of device that can be fabricated is a heterostructure, in which layers of different compounds are stacked in a single direction. Modern deposition techniques like electron beam epitaxy, in which atomic layers of different materials are deposited one at a time creating the device, are capable of fabricating heterostructures with atomic precision. We propose a technique to study heterostructures composed of strongly correlated materials out of equilibrium. By using the Keldysh Green's function formalism in the dynamical mean field theory (DMFT) framework the properties of a multilayered device are analyzed. The system is composed of infinite dimensional 2D lattices, stacked in the z direction. The first and last planes are then connected to a bulk reservoir, and several metallic planes are used to connect the bulk reservoir to the barrier region. The barrier region is the system of interest, also known as the device. The device is composed of a number of planes where the system correlations have been turned on. The correlations are then model by using the Falicov-Kimball Hamiltonian. The device is then connected to the bulk once again from the opposite side using metallic planes creating a symmetric system. In order to study the non equilibrium properties of the device a linear vector potential A(t) = A0 + tE is turned on a long time in the past for a unit of time and then turned off. This in turn will create a current in the bulk, in effect current biasing the device, as opposed to a voltage bias in which opposite sides of the device are held to a different potential. In this document we will explain the importance of the subject, we will derive and develop the algorithm

  7. Simulation of electron transport during electron-beam-induced deposition of nanostructures

    PubMed Central

    Jeschke, Harald O; Valentí, Roser

    2013-01-01

    Summary We present a numerical investigation of energy and charge distributions during electron-beam-induced growth of tungsten nanostructures on SiO2 substrates by using a Monte Carlo simulation of the electron transport. This study gives a quantitative insight into the deposition of energy and charge in the substrate and in the already existing metallic nanostructures in the presence of the electron beam. We analyze electron trajectories, inelastic mean free paths, and the distribution of backscattered electrons in different compositions and at different depths of the deposit. We find that, while in the early stages of the nanostructure growth a significant fraction of electron trajectories still interacts with the substrate, when the nanostructure becomes thicker the transport takes place almost exclusively in the nanostructure. In particular, a larger deposit density leads to enhanced electron backscattering. This work shows how mesoscopic radiation-transport techniques can contribute to a model that addresses the multi-scale nature of the electron-beam-induced deposition (EBID) process. Furthermore, similar simulations can help to understand the role that is played by backscattered electrons and emitted secondary electrons in the change of structural properties of nanostructured materials during post-growth electron-beam treatments. PMID:24367747

  8. Electron transport in magnetrons by a posteriori Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Costin, C.; Minea, T. M.; Popa, G.

    2014-02-01

    Electron transport across magnetic barriers is crucial in all magnetized plasmas. It governs not only the plasma parameters in the volume, but also the fluxes of charged particles towards the electrodes and walls. It is particularly important in high-power impulse magnetron sputtering (HiPIMS) reactors, influencing the quality of the deposited thin films, since this type of discharge is characterized by an increased ionization fraction of the sputtered material. Transport coefficients of electron clouds released both from the cathode and from several locations in the discharge volume are calculated for a HiPIMS discharge with pre-ionization operated in argon at 0.67 Pa and for very short pulses (few µs) using the a posteriori Monte Carlo simulation technique. For this type of discharge electron transport is characterized by strong temporal and spatial dependence. Both drift velocity and diffusion coefficient depend on the releasing position of the electron cloud. They exhibit minimum values at the centre of the race-track for the secondary electrons released from the cathode. The diffusion coefficient of the same electrons increases from 2 to 4 times when the cathode voltage is doubled, in the first 1.5 µs of the pulse. These parameters are discussed with respect to empirical Bohm diffusion.

  9. Molecular electronics: Some views on transport junctions and beyond

    PubMed Central

    Joachim, Christian; Ratner, Mark A.

    2005-01-01

    The field of molecular electronics comprises a fundamental set of issues concerning the electronic response of molecules as parts of a mesoscopic structure and a technology-facing area of science. We will overview some important aspects of these subfields. The most advanced ideas in the field involve the use of molecules as individual logic or memory units and are broadly based on using the quantum state space of the molecule. Current work in molecular electronics usually addresses molecular junction transport, where the molecule acts as a barrier for incoming electrons: This is the fundamental Landauer idea of “conduction as scattering” generalized to molecular junction structures. Another point of view in terms of superexchange as a guiding mechanism for coherent electron transfer through the molecular bridge is discussed. Molecules generally exhibit relatively strong vibronic coupling. The last section of this overview focuses on vibronic effects, including inelastic electron tunneling spectroscopy, hysteresis in junction charge transport, and negative differential resistance in molecular transport junctions. PMID:15956192

  10. Silicon Carbide Sensors and Electronics for Harsh Environment Applications

    NASA Technical Reports Server (NTRS)

    Evans, Laura J.

    2007-01-01

    Silicon carbide (SiC) semiconductor has been studied for electronic and sensing applications in extreme environment (high temperature, extreme vibration, harsh chemical media, and high radiation) that is beyond the capability of conventional semiconductors such as silicon. This is due to its near inert chemistry, superior thermomechanical and electronic properties that include high breakdown voltage and wide bandgap. An overview of SiC sensors and electronics work ongoing at NASA Glenn Research Center (NASA GRC) will be presented. The main focus will be two technologies currently being investigated: 1) harsh environment SiC pressure transducers and 2) high temperature SiC electronics. Work highlighted will include the design, fabrication, and application of SiC sensors and electronics, with recent advancements in state-of-the-art discussed as well. These combined technologies are studied for the goal of developing advanced capabilities for measurement and control of aeropropulsion systems, as well as enhancing tools for exploration systems.

  11. Invisible transportation infrastructure technology to mitigate energy and environment.

    PubMed

    Hossain, Md Faruque

    2017-01-01

    Traditional transportation infrastructure built by heat trapping products and the transportation vehiles run by fossil fuel, both causing deadly climate change. Thus, a new technology of invisible Flying Transportation system has been proposed to mitigate energy and environmental crisis caused by traditional infrastructure system. Underground Maglev system has been modeled to be constructed for all transportation systems to run the vehicle smoothly just over two feet over the earth surface by propulsive and impulsive force at flying stage. A wind energy modeling has also been added to meet the vehicle's energy demand when it runs on a non-maglev area. Naturally, all maglev infrastructures network to be covered by evergreen herb except pedestrian walkways to absorb CO2, ambient heat, and moisture (vapor) from the surrounding environment to make it cool. The research revealed that the vehicle will not require any energy since it will run by superconducting electromagnetic force while it runs on a maglev infrastructure area and directed by wind energy while it runs on non-maglev area. The proposed maglev transportation infrastructure technology will indeed be an innovative discovery in modern engineering science which will reduce fossil fuel energy consumption and climate change dramatically.

  12. Molecular modeling of inelastic electron transport in molecular junctions

    NASA Astrophysics Data System (ADS)

    Jiang, Jun; Kula, Mathias; Luo, Yi

    2008-09-01

    A quantum chemical approach for the modeling of inelastic electron tunneling spectroscopy of molecular junctions based on scattering theory is presented. Within a harmonic approximation, the proposed method allows us to calculate the electron-vibration coupling strength analytically, which makes it applicable to many different systems. The calculated inelastic electron transport spectra are often in very good agreement with their experimental counterparts, allowing the revelation of detailed information about molecular conformations inside the junction, molecule-metal contact structures, and intermolecular interaction that is largely inaccessible experimentally.

  13. Transport Experiments on 2D Correlated Electron Physics in Semiconductors

    SciTech Connect

    Tsui, Daniel

    2014-03-24

    This research project was designed to investigate experimentally the transport properties of the 2D electrons in Si and GaAs, two prototype semiconductors, in several new physical regimes that were previously inaccessible to experiments. The research focused on the strongly correlated electron physics in the dilute density limit, where the electron potential energy to kinetic energy ratio rs>>1, and on the fractional quantum Hall effect related physics in nuclear demagnetization refrigerator temperature range on samples with new levels of purity and controlled random disorder.

  14. Requirement for Coenzyme Q in Plasma Membrane Electron Transport

    NASA Astrophysics Data System (ADS)

    Sun, I. L.; Sun, E. E.; Crane, F. L.; Morre, D. J.; Lindgren, A.; Low, H.

    1992-12-01

    Coenzyme Q is required in the electron transport system of rat hepatocyte and human erythrocyte plasma membranes. Extraction of coenzyme Q from the membrane decreases NADH dehydrogenase and NADH:oxygen oxidoreductase activity. Addition of coenzyme Q to the extracted membrane restores the activity. Partial restoration of activity is also found with α-tocopherylquinone, but not with vitamin K_1. Analogs of coenzyme Q inhibit NADH dehydrogenase and oxidase activity and the inhibition is reversed by added coenzyme Q. Ferricyanide reduction by transmembrane electron transport from HeLa cells is inhibited by coenzyme Q analogs and restored with added coenzyme Q10. Reduction of external ferricyanide and diferric transferrin by HeLa cells is accompanied by proton release from the cells. Inhibition of the reduction by coenzyme Q analogs also inhibits the proton release, and coenzyme Q10 restores the proton release activity. Trans-plasma membrane electron transport stimulates growth of serum-deficient cells, and added coenzyme Q10 increases growth of HeLa (human adenocarcinoma) and BALB/3T3 (mouse fibroblast) cells. The evidence is consistent with a function for coenzyme Q in a trans-plasma membrane electron transport system which influences cell growth.

  15. Investigation of electron beam transport in a helical undulator

    SciTech Connect

    Jeong, Y.U.; Lee, B.C.; Kim, S.K.

    1995-12-31

    Lossless transport of electrons through the undulator is essential for CW operation of the FELs driven by recirculating electrostatic accelerators. We calculate the transport ratio of an electron beam in a helical undulator by using a 3-D simulation code and compare the results with the experimental results. The energy and the current of the electron beam are 400 keV and 2 A, respectively. The 3-D distribution of the magnetic field of a practical permanent-magnet helical undulator is measured and is used in the calculations. The major parameters of the undutlator are : period = 32 mm, number of periods = 20, number of periods in adiabatic region = 3.5, magnetic field strength = 1.3 kG. The transport ratio is very sensitive to the injection condition of the electron beam such as the emittance, the diameter, the divergence, etc.. The injection motion is varied in the experiments by changing the e-gun voltage or the field strength of the focusing magnet located at the entrance of the undulator. It is confirmed experimentally and with simulations that most of the beam loss occurs at the adiabatic region of the undulator regardless of the length of the adiabatic region The effect of axial guiding magnetic field on the beam finish is investigated. According to the simulations, the increase of the strength of axial magnetic field from 0 to 1 kG results in the increase of the transport ratio from 15 % to 95%.

  16. ELECTRONIC AND TRANSPORT PROPERTIES OF THERMOELECTRIC Ru2Si3

    NASA Astrophysics Data System (ADS)

    Singh, David J.; Parker, David

    2013-08-01

    We report calculations of the doping and temperature dependent thermopower of Ru2Si3 based on Boltzmann transport theory and the first principles electronic structure. We find that the performance reported to date can be significantly improved by optimization of the doping level and that ultimately n-type should have higher ZT than p-type.

  17. Electronic transport in gadolinium atomic-size contacts

    NASA Astrophysics Data System (ADS)

    Olivera, B.; Salgado, C.; Lado, J. L.; Karimi, A.; Henkel, V.; Scheer, E.; Fernández-Rossier, J.; Palacios, J. J.; Untiedt, C.

    2017-02-01

    We report on the fabrication, transport measurements, and density functional theory (DFT) calculations of atomic-size contacts made of gadolinium (Gd). Gd is known to have local moments mainly associated with f electrons. These coexist with itinerant s and d bands that account for its metallic character. Here we explore whether and how the local moments influence electronic transport properties at the atomic scale. Using both scanning tunneling microscope and lithographic mechanically controllable break junction techniques under cryogenic conditions, we study the conductance of Gd when only few atoms form the junction between bulk electrodes made of the very same material. Thousands of measurements show that Gd has an average lowest conductance, attributed to single-atom contact, below 2/e2 h . Our DFT calculations for monostrand chains anticipate that the f bands are fully spin polarized and insulating and that the conduction may be dominated by s , p , and d bands. We also analyze the electronic transport for model nanocontacts using the nonequilibrium Green's function formalism in combination with DFT. We obtain an overall good agreement with the experimental results for zero bias and show that the contribution to the electronic transport from the f channels is negligible and that from the d channels is marginal.

  18. Transportation of a microwave environment over networks and the applications

    NASA Astrophysics Data System (ADS)

    Shoji, Yozo

    2012-01-01

    The concept of the transportation of a microwave environment over networks using a digitized Radio-on-Fibre (DRoF) technique as well as the concept of in-network microwave processing, which could make the concept of "wired and wireless network virtualization" into a reality, is discussed. The new applications to a radio-on-demand service (RoD), software-defined radio-aware network (SDRAN), and microwave environments cloud are introduced. 10-Gbps Ethernet based microwave-to-network interface converter (MiNIC) are developed and the transportation of multiple digital TV broadcasting signals is demonstrated. It is shown that the MiNIC should use more than 8-bits resolution in digitization of a microwave environment when 7 channels of TV signals are included in it. The concept of remote microwave environments observation over networks is demonstrated, where the frequency channel and received signal strength indication (RSSI) of the detected digital TV broadcasting signals are remotely monitored.

  19. Waiting time distribution for electron transport in a molecular junction with electron-vibration interaction

    NASA Astrophysics Data System (ADS)

    Kosov, Daniel S.

    2017-02-01

    On the elementary level, electronic current consists of individual electron tunnelling events that are separated by random time intervals. The waiting time distribution is a probability to observe the electron transfer in the detector electrode at time t +τ given that an electron was detected in the same electrode at an earlier time t. We study waiting time distribution for quantum transport in a vibrating molecular junction. By treating the electron-vibration interaction exactly and molecule-electrode coupling perturbatively, we obtain the master equation and compute the distribution of waiting times for electron transport. The details of waiting time distributions are used to elucidate microscopic mechanism of electron transport and the role of electron-vibration interactions. We find that as nonequilibrium develops in the molecular junction, the skewness and dispersion of the waiting time distribution experience stepwise drops with the increase of the electric current. These steps are associated with the excitations of vibrational states by tunnelling electrons. In the strong electron-vibration coupling regime, the dispersion decrease dominates over all other changes in the waiting time distribution as the molecular junction departs far away from the equilibrium.

  20. Neoclassical electron and ion transport in toroidally rotating plasmas

    SciTech Connect

    Sugama, H.; Horton, W.

    1997-06-01

    Neoclassical transport processes of electrons and ions are investigated in detail for toroidally rotating axisymmetric plasmas with large flow velocities on the order of the ion thermal speed. The Onsager relations for the flow-dependent neoclassical transport coefficients are derived from the symmetry properties of the drift kinetic equation with the self-adjoint collision operator. The complete neoclassical transport matrix with the Onsager symmetry is obtained for the rotating plasma consisting of electrons and single-species ions in the Pfirsch{endash}Schl{umlt u}ter and banana regimes. It is found that the inward banana fluxes of particles and toroidal momentum are driven by the parallel electric field, which are phenomena coupled through the Onsager symmetric off-diagonal coefficients to the parallel currents caused by the radial thermodynamic forces conjugate to the inward fluxes, respectively. {copyright} {ital 1997 American Institute of Physics.}

  1. Pair tunneling resonance in the single-electron transport regime.

    PubMed

    Leijnse, M; Wegewijs, M R; Hettler, M H

    2009-10-09

    We predict a new electron pair tunneling (PT) resonance in nonlinear transport through quantum dots with positive charging energies exceeding the broadening due to thermal and quantum fluctuations. The PT resonance shows up in the single-electron transport (SET) regime as a peak in the derivative of the nonlinear conductance, d(2)I/dV(2), when the electrochemical potential of one electrode matches the average of two subsequent charge addition energies. For a single level quantum dot (Anderson model) we find the analytic peak shape and the dependence on temperature, magnetic field, and junction asymmetry and compare with the inelastic cotunneling peak which is of the same order of magnitude. In experimental transport spectroscopy the PT resonance may be mistaken for a weak SET resonance judging only by the voltage dependence of its position. Our results provide essential clues to avoid such erroneous interpretation.

  2. High Temperature Electronics for Intelligent Harsh Environment Sensors

    NASA Technical Reports Server (NTRS)

    Evans, Laura J.

    2008-01-01

    The development of intelligent instrumentation systems is of high interest in both public and private sectors. In order to obtain this ideal in extreme environments (i.e., high temperature, extreme vibration, harsh chemical media, and high radiation), both sensors and electronics must be developed concurrently in order that the entire system will survive for extended periods of time. The semiconductor silicon carbide (SiC) has been studied for electronic and sensing applications in extreme environment that is beyond the capability of conventional semiconductors such as silicon. The advantages of SiC over conventional materials include its near inert chemistry, superior thermomechanical properties in harsh environments, and electronic properties that include high breakdown voltage and wide bandgap. An overview of SiC sensors and electronics work ongoing at NASA Glenn Research Center (NASA GRC) will be presented. The main focus will be two technologies currently being investigated: 1) harsh environment SiC pressure transducers and 2) high temperature SiC electronics. Work highlighted will include the design, fabrication, and application of SiC sensors and electronics, with recent advancements in state-of-the-art discussed as well. These combined technologies are studied for the goal of developing advanced capabilities for measurement and control of aeropropulsion systems, as well as enhancing tools for exploration systems.

  3. Energy-filtered Electron Transport Structures for Low-power Low-noise 2-D Electronics.

    PubMed

    Pan, Xuan; Qiu, Wanzhi; Skafidas, Efstratios

    2016-10-31

    In addition to cryogenic techniques, energy filtering has the potential to achieve high-performance low-noise 2-D electronic systems. Assemblies based on graphene quantum dots (GQDs) have been demonstrated to exhibit interesting transport properties, including resonant tunnelling. In this paper, we investigate GQDs based structures with the goal of producing energy filters for next generation lower-power lower-noise 2-D electronic systems. We evaluate the electron transport properties of the proposed GQD device structures to demonstrate electron energy filtering and the ability to control the position and magnitude of the energy passband by appropriate device dimensioning. We also show that the signal-to-thermal noise ratio performance of the proposed nanoscale device can be modified according to device geometry. The tunability of two-dimensional GQD structures indicates a promising route for the design of electron energy filters to produce low-power and low-noise electronics.

  4. Energy-filtered Electron Transport Structures for Low-power Low-noise 2-D Electronics

    PubMed Central

    Pan, Xuan; Qiu, Wanzhi; Skafidas, Efstratios

    2016-01-01

    In addition to cryogenic techniques, energy filtering has the potential to achieve high-performance low-noise 2-D electronic systems. Assemblies based on graphene quantum dots (GQDs) have been demonstrated to exhibit interesting transport properties, including resonant tunnelling. In this paper, we investigate GQDs based structures with the goal of producing energy filters for next generation lower-power lower-noise 2-D electronic systems. We evaluate the electron transport properties of the proposed GQD device structures to demonstrate electron energy filtering and the ability to control the position and magnitude of the energy passband by appropriate device dimensioning. We also show that the signal-to-thermal noise ratio performance of the proposed nanoscale device can be modified according to device geometry. The tunability of two-dimensional GQD structures indicates a promising route for the design of electron energy filters to produce low-power and low-noise electronics. PMID:27796343

  5. Energy-filtered Electron Transport Structures for Low-power Low-noise 2-D Electronics

    NASA Astrophysics Data System (ADS)

    Pan, Xuan; Qiu, Wanzhi; Skafidas, Efstratios

    2016-10-01

    In addition to cryogenic techniques, energy filtering has the potential to achieve high-performance low-noise 2-D electronic systems. Assemblies based on graphene quantum dots (GQDs) have been demonstrated to exhibit interesting transport properties, including resonant tunnelling. In this paper, we investigate GQDs based structures with the goal of producing energy filters for next generation lower-power lower-noise 2-D electronic systems. We evaluate the electron transport properties of the proposed GQD device structures to demonstrate electron energy filtering and the ability to control the position and magnitude of the energy passband by appropriate device dimensioning. We also show that the signal-to-thermal noise ratio performance of the proposed nanoscale device can be modified according to device geometry. The tunability of two-dimensional GQD structures indicates a promising route for the design of electron energy filters to produce low-power and low-noise electronics.

  6. Electronic properties and quantum transport in Graphene-based nanostructures

    NASA Astrophysics Data System (ADS)

    Dubois, S. M.-M.; Zanolli, Z.; Declerck, X.; Charlier, J.-C.

    2009-11-01

    Carbon nanotubes (CNTs) and graphene nanoribbons (GNRs) represent a novel class of low-dimensional materials. All these graphene-based nanostructures are expected to display the extraordinary electronic, thermal and mechanical properties of graphene and are thus promising candidates for a wide range of nanoscience and nanotechnology applications. In this paper, the electronic and quantum transport properties of these carbon nanomaterials are reviewed. Although these systems share the similar graphene electronic structure, confinement effects are playing a crucial role. Indeed, the lateral confinement of charge carriers could create an energy gap near the charge neutrality point, depending on the width of the ribbon, the nanotube diameter, the stacking of the carbon layers regarding the different crystallographic orientations involved. After reviewing the transport properties of defect-free systems, doping and topological defects (including edge disorder) are also proposed as tools to taylor the quantum conductance in these materials. Their unusual electronic and transport properties promote these carbon nanomaterials as promising candidates for new building blocks in a future carbon-based nanoelectronics, thus opening alternatives to present silicon-based electronics devices.

  7. Characteristics of electron internal transport barrier in Heliotron J

    NASA Astrophysics Data System (ADS)

    Kenmochi, N.; Minami, T.; Takahashi, C.; Mochizuki, S.; Nishioka, K.; Kobayashi, S.; Nagasaki, K.; Nakamura, Y.; Okada, H.; Kado, S.; Yamamoto, S.; Ohshima, S.; Konoshima, S.; Weir, G. M.; Otani, Y.; Mizuuchi, T.

    2017-05-01

    The formation of an electron internal transport barrier (eITB) has been observed for the first time with centrally focused electron cyclotron heating (ECH) microwaves injected into plasma in Heliotron J. When the heating power per electron density ({P}{ECH}/{\\bar{n}}{{e}}) exceeds a threshold of 250× {10}-19 {kW} {{{m}}}3, transient increases of both the central T e and the core T e gradients are observed. A neoclassical (NC) calculation using the Sugama-Nishimura moment method predicts that the large positive radial electric field (E r) is formed in the core region. Heat transport analysis shows a significant reduction of the effective electron thermal diffusivity in the plasma with the eITB related to that without the eITB. The large gap between the experimentally obtained effective thermal diffusivity and the NC thermal diffusivity suggests that the suppression of anomalous transport contributes to the core improved confinement of the eITB plasma. The electron cyclotron emission measurement shows both the transient increase and the hysteresis phenomena during the eITB formation.

  8. Crystallization of germanium-carbon alloys -- Structure and electronic transport

    SciTech Connect

    John, T.M.; Blaesing, J.; Veit, P.; Druesedau, T.

    1997-07-01

    Amorphous Ge{sub 1{minus}x}C{sub x} alloys were deposited by rf-magnetron sputtering from a germanium target in methane-argon atmosphere. Structural investigations were performed by means of wide and small angle X-ray scattering, X-ray reflectometry and cross-sectional transmission electron microscopy. The electronic transport properties were characterized using Hall-measurements and temperature depended conductivity. The results of X-ray techniques together with the electron microscopy clearly prove the existence of a segregation of the electronic conductivity in the as-prepared films follows the Mott' T{sup {minus}1/4} law, indicating transport by a hopping process. After annealing at 870 K, samples with x {le} 0.4 show crystallization of the Ge-clusters with a crystallite size being a function of x. After Ge-crystallization, the conductivity increases by 4 to 5 orders of magnitude. Above room temperature, electronic transport is determined by a thermally activated process. For lower temperatures, the {sigma}(T) curves show a behavior which is determined by the crystallite size and the free carrier concentration, both depending on the carbon content.

  9. Stopping and transport of fast electrons in superdense matter

    SciTech Connect

    Okabayashi, A.; Habara, H.; Yabuuchi, T.; Iwawaki, T.; Tanaka, K. A.

    2013-08-15

    Studied is the stopping and transport of relativistic fast electrons in the vicinity of compressed dense plasma core relevant to fast ignition. Electromagnetic cascade Monte-Carlo is coupled to 2D-PIC simulation. The 2D PIC simulates input electron energy spectrum and angular dependence. The electron energy distributions after passing through the plasma core are calculated at different viewing angles, which well agree with the experiment below several MeV energy range. The implications of calculated results as to collisional damping on several MeV electrons are discussed with the theory based on the stopping power model. The spatial distribution of plasma temperature is also estimated via deposited energy by fast electrons, showing the strong heating at the core surface.

  10. Transport properties of copper phthalocyanine based organic electronic devices

    NASA Astrophysics Data System (ADS)

    Schuster, C.; Kraus, M.; Opitz, A.; Brütting, W.; Eckern, U.

    2009-12-01

    Ambipolar charge carrier transport in Copper phthalocyanine (CuPc) is studied experimentally in field-effect transistors and metal-insulator-semiconductor diodes at various temperatures. The electronic structure and the transport properties of CuPc attached to leads are calculated using density functional theory and scattering theory at the non-equilibrium Green’s function level. We discuss, in particular, the electronic structure of CuPc molecules attached to gold chains in different geometries to mimic the different experimental setups. The combined experimental and theoretical analysis explains the dependence of the mobility and the transmission coefficient on the charge carrier type (electrons or holes) and on the contact geometry. We demonstrate the correspondence between our experimental results on thick films and our theoretical studies of single molecule contacts. Preliminary results for fluorinated CuPc are discussed.

  11. Electron transport mechanisms in polymer-carbon sphere composites

    NASA Astrophysics Data System (ADS)

    Nieves, Cesar A.; Ramos, Idalia; Pinto, Nicholas J.; Zimbovskaya, Natalya A.

    2016-07-01

    A set of uniform carbon microspheres (CSs) whose diameters have the order of 0.125 μm to 10 μm was prepared from aqueous sucrose solution by means of hydrothermal carbonization of sugar molecules. A pressed pellet was composed by mixing CSs with polyethylene oxide (PEO). Electrical characterization of the pellet was carried out showing Ohmic current-voltage characteristics and temperature-dependent conductivity in the range of 80 K electron transport. It was shown that thermally induced electron tunneling between adjacent spheres may take on an important part in the electron transport through the CS/PEO composites.

  12. Transport in nanoscale systems: hydrodynamics, turbulence, and local electron heating

    NASA Astrophysics Data System (ADS)

    di Ventra, Massimiliano

    2007-03-01

    Transport in nanoscale systems is usually described as an open-boundary scattering problem. This picture, however, says nothing about the dynamical onset of steady states, their microscopic nature, or their dependence on initial conditions [1]. In order to address these issues, I will first describe the dynamical many-particle state via an effective quantum hydrodynamic theory [2]. This approach allows us to predict a series of novel phenomena like turbulence of the electron liquid [2], local electron heating in nanostructures [3], and the effect of electron viscosity on resistance [4]. I will provide both analytical results and numerical examples of first-principles electron dynamics in nanostructures using the above approach. I will also discuss possible experimental tests of our predictions. Work supported in part by NSF and DOE. [1] N. Bushong, N. Sai and M. Di Ventra, ``Approach to steady-state transport in nanoscale systems'' Nano Letters, 5 2569 (2005); M. Di Ventra and T.N. Todorov, ``Transport in nanoscale systems: the microcanonical versus grand-canonical picture,'' J. Phys. Cond. Matt. 16, 8025 (2004). [2] R. D'Agosta and M. Di Ventra, ``Hydrodynamic approach to transport and turbulence in nanoscale conductors,'' cond-mat/05123326; J. Phys. Cond. Matt., in press. [3] R. D'Agosta, N. Sai and M. Di Ventra, ``Local electron heating in nanoscale conductors,'' cond-mat/0605312; Nano Letters, in press. [4] N. Sai, M. Zwolak, G. Vignale and M. Di Ventra, ``Dynamical corrections to the DFT-LDA electron conductance in nanoscale systems,'' Phys. Rev. Lett. 94, 186810 (2005).

  13. Ultrafast electron transport in graphene and magnetic nanostructures

    NASA Astrophysics Data System (ADS)

    Turchinovich, Dmitry

    2016-03-01

    Ultrafast terahertz spectroscopy is an ideal tool for observation of dynamics of charge, lattice and spin in solids on the most elementary timescale: in the regime ωτ ~ 1, where ω is the electromagnetic wave oscillation frequency, and τ is the characteristic timescale at which the fundamental phenomena in the three subsystems comprising the solid occur. In this paper two case studies will be discussed. (i) Ultrafast electron transport in graphene. We will show, that the free-carrier conductivity of graphene in arbitrary ultrafast, (sub-)picosecond electric fields is defined by the thermodynamic balance maintained within the electronic structure of graphene acting as thermalized electron gas. Within this simple thermodynamic picture, the electron gas quasi-instantaneously increases its temperature by absorbing the energy of driving ultrafast electric field, and at the same time cools down via a time-retarded, few picosecond-long process of phonon emission. The asymmetry in electron heating and cooling dynamics leads to heat accumulation in the electron population of graphene, concomitantly lowering the chemical potential for hotter electrons, and thereby reducing the intraband conductivity of graphene - an effect crucially important for understanding of ultrafast graphene transistors and photodetectors. (ii) We will also discuss the fundamental observation of spin-controlled electron conduction of Fermilevel electrons in ferromagnetic metals, and will directly quantify the Mott picture of conduction in ferromagnets - the effect directly employed in modern magnetic sensor technologies such as giant magnetoresistance.

  14. Hot Electrons and Energy Transport in Metals at MK Temperatures.

    NASA Astrophysics Data System (ADS)

    Roukes, Michael Lee

    Using a new technique involving the generation of hot carriers, we directly measure energy loss lifetimes for electrons in impure metals at mK temperatures. At these temperatures very weak inelastic scattering processes determine energy transport out of the electron gas. A temperature difference between the electron gas and the lattice can be induced by applying an extremely small electric field (of order 1 (mu)V/cm at 25 mK). This temperature difference reflects the rate at which electrons lose energy to the surroundings. The experiment is carried out using a pair of interdigitated thin film resistors mounted on a millidegree demagnetization cryostat: we obtain electron temperature directly by observing current fluctuations. Noise generated by the resistors is measured using an ultra-sensitive two -channel dc SQUID system, providing femtoamp resolution at KHz frequencies. A dc voltage applied across one resistor imposes the bias field causing electron heating. Phonon temperature in the metal lattice is obtained by measuring noise from a second (unbiased) resistor, which is tightly coupled thermally to the first (biased). Our measurements show that electron heating follows an E('2/5) power law in the regime where electron temperature is largely determined by the electric field, E. This implies a T('-3) law for the energy loss lifetime, suggesting electron -acoustic phonon processes dominate. In the mK temperature regime the conductivity is impurity limited and remains ohmic, even as the electrons heat. Assuming a T('3) dependence and extrapolating our measured rates to higher temperatures, we find agreement with electron-phonon rates measured above 1K in clean bulk metals. This contrasts with results from weak localization experiments showing a power law differing from T('3) and much faster rates. This difference arises because weak localization experiments measure the electron phase coherence lifetime; our electron heating experiments, however, measure an energy

  15. Electron Beam Freeform Fabrication in the Space Environment

    NASA Technical Reports Server (NTRS)

    Taminger, Karen M.; Hafley, Robert A.

    2007-01-01

    This viewgraph presentation describes the effect of microgravity on the fabrication of electron beam freeform (EBF) in aerospace environments. The contents include: 1) Electron Beam Freeform Fabrication (EBF3) Process Description; 2) Portable Electron Beam Freeform Fabrication System at NASA LaRC; 3) Electron Beam Freeform Fabrication in the Space Environment; 4) Effect of Gravity on Surface Tension; 5) Effect of Deposit Height on Cooling Path; 6) Microgravity Testing Aboard JSC's C-9; 7) Typical Test Flight Plates; 8) Direction and Height Trials for Process Control; 9) Effect of Wire Entry Direction into Molten Pool; 10) Microstructure of Single Layer EBF Deposits; 11) 0-g Deposit with Incorrect Standoff Distance; 12) Successful Demonstration of EBF in 0-g; and 13) Conclusion.

  16. Electronic transport through zigzag/armchair graphene nanoribbon heterojunctions.

    PubMed

    Li, Xiao-Fei; Wang, Ling-Ling; Chen, Ke-Qiu; Luo, Yi

    2012-03-07

    The electronic transport properties of a graphene nanoribbon (GNR) are known to be sensitive to its width, edges and defects. We investigate the electronic transport properties of a graphene nanoribbon heterojunction constructed by fusing a zigzag and an armchair graphene nanoribbon (zGNR/aGNR) side by side. First principles results reveal that the heterojunction can be either metallic or semiconducting, depending on the width of the nanoribbons. Intrinsic rectification behaviors have been observed, which are largely sensitive to the connection length between the zGNR and aGNR. The microscopic origins of the rectification behavior have been revealed. We find that the carrier type can alter from electrons to holes with the bias voltage changing from negative to positive; the asymmetrical transmission spectra of electrons and holes induced by the interface defects directly results in the rectification behavior. The results suggest that any methods which can enhance the asymmetry of the transmission spectra between holes and electrons could be used to improve the rectification behavior in the zGNR/aGNR heterojunction. Our findings could be useful for designing graphene based electronic devices.

  17. Built Environment Influences on Healthy Transportation Choices: Bicycling versus Driving

    PubMed Central

    Brauer, Michael; Setton, Eleanor M.; Teschke, Kay

    2010-01-01

    A growing body of evidence links the built environment to physical activity levels, health outcomes, and transportation behaviors. However, little of this research has focused on cycling, a sustainable transportation option with great potential for growth in North America. This study examines associations between decisions to bicycle (versus drive) and the built environment, with explicit consideration of three different spatial zones that may be relevant in travel behavior: trip origins, trip destinations, and along the route between. We analyzed 3,280 utilitarian bicycle and car trips in Metro Vancouver, Canada made by 1,902 adults, including both current and potential cyclists. Objective measures were developed for built environment characteristics related to the physical environment, land use patterns, the road network, and bicycle-specific facilities. Multilevel logistic regression was used to model the likelihood that a trip was made by bicycle, adjusting for trip distance and personal demographics. Separate models were constructed for each spatial zone, and a global model examined the relative influence of the three zones. In total, 31% (1,023 out of 3,280) of trips were made by bicycle. Increased odds of bicycling were associated with less hilliness; higher intersection density; less highways and arterials; presence of bicycle signage, traffic calming, and cyclist-activated traffic lights; more neighborhood commercial, educational, and industrial land uses; greater land use mix; and higher population density. Different factors were important within each spatial zone. Overall, the characteristics of routes were more influential than origin or destination characteristics. These findings indicate that the built environment has a significant influence on healthy travel decisions, and spatial context is important. Future research should explicitly consider relevant spatial zones when investigating the relationship between physical activity and urban form. PMID

  18. Built environment influences on healthy transportation choices: bicycling versus driving.

    PubMed

    Winters, Meghan; Brauer, Michael; Setton, Eleanor M; Teschke, Kay

    2010-12-01

    A growing body of evidence links the built environment to physical activity levels, health outcomes, and transportation behaviors. However, little of this research has focused on cycling, a sustainable transportation option with great potential for growth in North America. This study examines associations between decisions to bicycle (versus drive) and the built environment, with explicit consideration of three different spatial zones that may be relevant in travel behavior: trip origins, trip destinations, and along the route between. We analyzed 3,280 utilitarian bicycle and car trips in Metro Vancouver, Canada made by 1,902 adults, including both current and potential cyclists. Objective measures were developed for built environment characteristics related to the physical environment, land use patterns, the road network, and bicycle-specific facilities. Multilevel logistic regression was used to model the likelihood that a trip was made by bicycle, adjusting for trip distance and personal demographics. Separate models were constructed for each spatial zone, and a global model examined the relative influence of the three zones. In total, 31% (1,023 out of 3,280) of trips were made by bicycle. Increased odds of bicycling were associated with less hilliness; higher intersection density; less highways and arterials; presence of bicycle signage, traffic calming, and cyclist-activated traffic lights; more neighborhood commercial, educational, and industrial land uses; greater land use mix; and higher population density. Different factors were important within each spatial zone. Overall, the characteristics of routes were more influential than origin or destination characteristics. These findings indicate that the built environment has a significant influence on healthy travel decisions, and spatial context is important. Future research should explicitly consider relevant spatial zones when investigating the relationship between physical activity and urban form.

  19. Vibronic coupling effect on the electron transport through molecules

    NASA Astrophysics Data System (ADS)

    Tsukada, Masaru; Mitsutake, Kunihiro

    2007-03-01

    Electron transport through molecular bridges or molecular layers connected to nano-electrodes is determined by the combination of coherent and dissipative processes, controlled by the electron-vibron coupling, transfer integrals between the molecular orbitals, applied electric field and temperature. We propose a novel theoretical approach, which combines ab initio molecular orbital method with analytical many-boson model. As a case study, the long chain model of the thiophene oligomer is solved by a variation approach. Mixed states of moderately extended molecular orbital states mediated and localised by dress of vibron cloud are found as eigen-states. All the excited states accompanied by multiple quanta of vibration can be solved, and the overall carrier transport properties including the conductance, mobility, dissipation spectra are analyzed by solving the master equation with the transition rates estimated by the golden rule. We clarify obtained in a uniform systematic way, how the transport mode changes from a dominantly coherent transport to the dissipative hopping transport.

  20. Current Issues in Electron and Positron Transport Theory

    NASA Astrophysics Data System (ADS)

    Robson, Robert

    2007-10-01

    In this paper we review the current status of transport theory for low energy electrons or positrons in gases, in the context of both kinetic theory and fluid modelling. In particular, we focus on the following issues: (i) Muliterm vs two-term representation of the velocity distribution function in solution of Boltzmann's equation; (ii) the effect of non-conservative collisions (attachment, ionization, positron annihilation) on transport properties; (iii) the enduring electron- hydrogen vibrational cross section controversy and possible implications for the Boltzmann equation itself; (iv) closure of the fluid equations and the heat flux ansatz; and (v) correct use of swarm transport coefficients in fluid modelling of low temperature plasmas. Both hydrodynamic and non-hydrodynamic examples will be given, with attention focussed on the Franck-Hertz experiment, particularly the ``window'' of fields in which oscillations of transport properties are produced, and the way in which electric and magnetic fields combine to affect transport properties. In collaboration with co-authors Z. LJ. Petrovi'c, Institute of Physics Belgrade, and R.D. White, James Cook University.

  1. Asymmetric electron transport realized by decoupling between molecule and electrode.

    PubMed

    Liu, Hongmei; Zhao, Jianwei; Boey, Freddy; Zhang, Hua

    2009-11-28

    We studied the contact coupling effect on the asymmetric electron transport in molecular junctions by the first-principles density functional theory incorporating with the non-equilibrium Green's function method. To realize the decoupling, a rigid saturated ring is inserted into the metallic electrode and conjugated molecular bridge (linear oligo phenylene ethynylene and cyclic porphine). As a tunneling barrier, the saturated ring reduces the conductance by 2-3 orders of magnitude. However, the electronic decoupling greatly improves the asymmetric electron transport. In the case of the linear system, the favorite direction of electron transport is from the strong coupling end to the weak coupling one with a rectification ratio of 5 at 2.0 V. In addition, the rectification performance is sensitive to the molecular proportion of the molecular wire length and the tunneling barrier width. When the same barrier is applied, shortening the length of conjugated part can reduce rectification performance. The mechanism of rectification is analyzed by means of the potential drop, the spatial distribution of the molecular orbitals and the transmission spectra.

  2. 75 FR 38605 - Surface Transportation Environment and Planning Cooperative Research Program (STEP)

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-02

    ... to implement this cooperative research program. Due to obligation limitations, recissions, and... Federal Highway Administration Surface Transportation Environment and Planning Cooperative Research...-LU) established the Surface Transportation Environment and Planning Cooperative Research Program...

  3. Theoretical descriptions of electron transport through single molecules: Developing design tools for molecular electronic devices

    NASA Astrophysics Data System (ADS)

    Carroll, Natalie R.

    There are vast numbers of organic compounds that could be considered for use in molecular electronics. Hence there is a need for efficient and economical screening tools. Here we develop theoretical methods to describe electron transport through individual molecules, the ultimate goal of which is to establish design tools for molecular electronic devices. To successfully screen a compound for its use as a device component requires a proper representation of the quantum mechanics of electron transmission. In this work we report the development of tools for the description of electron transmission that are: Charge self-consistent, valid in the presence of a finite applied potential field and (in some cases) explicitly time-dependent. In addition, the tools can be extended to any molecular system, including biosystems, because they are free of restrictive parameterizations. Two approaches are explored: (1) correlation of substituent parameter values (sigma), (commonly found in organic chemistry textbooks) to properties associated with electron transport, (2) explicit tracking of the time evolution of the wave function of a nonstationary electron. In (1) we demonstrate that the a correlate strongly with features of the charge migration process, establishing them as useful indicators of electronic properties. In (2) we employ a time-dependent description of electron transport through molecular junctions. To date, the great majority of theoretical treatments of electron transport in molecular junctions have been of the time-independent variety. Time dependence, however, is critical to such properties as switching speeds in binary computer components and alternating current conductance, so we explored methods based on time-dependent quantum mechanics. A molecular junction is modeled as a single molecule sandwiched between two clusters of close-packed metal atoms or other donor and acceptor groups. The time dependence of electron transport is investigated by initially

  4. Electronic transport in benzodifuran single-molecule transistors

    NASA Astrophysics Data System (ADS)

    Xiang, An; Li, Hui; Chen, Songjie; Liu, Shi-Xia; Decurtins, Silvio; Bai, Meilin; Hou, Shimin; Liao, Jianhui

    2015-04-01

    Benzodifuran (BDF) single-molecule transistors have been fabricated in electromigration break junctions for electronic measurements. The inelastic electron tunneling spectrum validates that the BDF molecule is the pathway of charge transport. The gating effect is analyzed in the framework of a single-level tunneling model combined with transition voltage spectroscopy (TVS). The analysis reveals that the highest occupied molecular orbital (HOMO) of the thiol-terminated BDF molecule dominates the charge transport through Au-BDF-Au junctions. Moreover, the energy shift of the HOMO caused by the gate voltage is the main reason for conductance modulation. In contrast, the electronic coupling between the BDF molecule and the gold electrodes, which significantly affects the low-bias junction conductance, is only influenced slightly by the applied gate voltage. These findings will help in the design of future molecular electronic devices.Benzodifuran (BDF) single-molecule transistors have been fabricated in electromigration break junctions for electronic measurements. The inelastic electron tunneling spectrum validates that the BDF molecule is the pathway of charge transport. The gating effect is analyzed in the framework of a single-level tunneling model combined with transition voltage spectroscopy (TVS). The analysis reveals that the highest occupied molecular orbital (HOMO) of the thiol-terminated BDF molecule dominates the charge transport through Au-BDF-Au junctions. Moreover, the energy shift of the HOMO caused by the gate voltage is the main reason for conductance modulation. In contrast, the electronic coupling between the BDF molecule and the gold electrodes, which significantly affects the low-bias junction conductance, is only influenced slightly by the applied gate voltage. These findings will help in the design of future molecular electronic devices. Electronic supplementary information (ESI) available: The fabrication procedure for BDF single

  5. Transport of the plasma sheet electrons to the geostationary distances

    NASA Astrophysics Data System (ADS)

    Ganushkina, N. Y.; Amariutei, O. A.; Shprits, Y.; Liemohn, M. W.

    2012-12-01

    The transport and acceleration of low energy electrons (10-250 keV) from the plasma sheet to the geostationary orbit were investigated. Two moderate storm events, which occurred on November 6-7, 1997 and June 12-14, 2005, were modeled using the Inner Magnetosphere Particle Transport and Acceleration model (IMPTAM) with the boundary set at 10 RE in the plasma sheet. The output of the IMPTAM model was compared to the observed electron fluxes in four energy ranges measured onboard the LANL spacecraft by the SOPA instrument. It was found that the large-scale convection in combination with substorm-associated impulsive fields are the drivers of the transport of plasma sheet electrons from 10 RE to geostationary orbit at 6.6 RE during storm times. The addition of radial diffusion had no significant influence on the modeled electron fluxes. At the same time, comparison between the modeled electron fluxes and observed ones showed two orders of difference most likely due to inaccuracy of electron boundary conditions and omission of the important loss processes due to wave-particle interactions. This did not allow us to accuractly reproduce the dynamics of 150-225 keV electron fluxes. The choice of the large-scale convection electric field model used in simulations did not significantly influence on the modeled electron fluxes, since there is not much difference between the equipotential contours given by the Volland-Stern and Boyle et al. [1997] models at the distances from 10 to 6.6 RE in the plasma sheet. Using the TS05 model for the background magnetic field instead of the T96 model resulted in larger deviations of the modeled electron fluxes from the observed ones due to specific features of the TS05 model. The increase in the modeled electron fluxes can be as large as three orders of magnitude when substorm-associated electromagnetic fields were taken into account. The obtained model distribution of low energy electron fluxes can be used as an input to the radiation

  6. Transport of the plasma sheet electrons to the geostationary distances

    NASA Astrophysics Data System (ADS)

    Ganushkina, N. Y.; Amariutei, O. A.; Shprits, Y. Y.; Liemohn, M. W.

    2013-01-01

    Abstract<p label="1">The <span class="hlt">transport</span> and acceleration of low-energy <span class="hlt">electrons</span> (50-250 keV) from the plasma sheet to the geostationary orbit were investigated. Two moderate storm events, which occurred on 6-7 November 1997 and 12-14 June 2005, were modeled using the Inner Magnetosphere Particle <span class="hlt">Transport</span> and Acceleration model (IMPTAM) with the boundary set at 10 RE in the plasma sheet. The output of the IMPTAM was compared to the observed <span class="hlt">electron</span> fluxes in four energy ranges (50-225 keV) measured by the Synchronous Orbit Particle Analyzer instrument onboard the Los Alamos National Laboratory spacecraft. It was found that the large-scale convection in combination with substorm-associated impulsive fields is the drivers of the <span class="hlt">transport</span> of plasma sheet <span class="hlt">electrons</span> from 10 RE to geostationary orbit at 6.6 RE during storm times. The addition of radial diffusion had no significant influence on the modeled <span class="hlt">electron</span> fluxes. At the same time, the modeled <span class="hlt">electron</span> fluxes are one (two) order(s) smaller than the observed ones for 50-150 keV (150-225 keV) <span class="hlt">electrons</span>, respectively, most likely due to inaccuracy of <span class="hlt">electron</span> boundary conditions. The loss processes due to wave-particle interactions were not considered. The choice of the large-scale convection electric field model used in simulations did not have a significant influence on the modeled <span class="hlt">electron</span> fluxes, since there is not much difference between the equipotential contours given by the Volland-Stern and the Boyle et al. (1997) models at distances from 10 to 6.6 RE in the plasma sheet. Using the TS05 model for the background magnetic field instead of the T96 model resulted in larger deviations of the modeled <span class="hlt">electron</span> fluxes from the observed ones due to specific features of the TS05 model. The increase in the modeled <span class="hlt">electron</span> fluxes can be as large as two orders of magnitude when substorm-associated electromagnetic fields were taken into account. The obtained model distribution of low-energy <span class="hlt">electron</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AIPA....7g5310Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AIPA....7g5310Y"><span>Strain modification on <span class="hlt">electronic</span> <span class="hlt">transport</span> of the phosphorene nanoribbon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yuan, Yawen; Cheng, Fang</p> <p>2017-07-01</p> <p>We demonstrate theoretically how local strains can be tailored to control quantum <span class="hlt">transport</span> of carriers on monolayer armchair and zigzag phosphorene nanoribbon. We find that the <span class="hlt">electron</span> tunneling is forbidden when the in-plane strain exceeds a critical value. The critical strain is different for different crystal orientation of the ribbons, widths, and incident energies. By tuning the Fermi energy and strain, the channels can be transited from opaque to transparent. Moreover, for the zigzag-phosphorene nanoribbon, the two-fold degenerate quasi-flat edge band splits completely under certain strain. These properties provide us an efficient way to control the <span class="hlt">transport</span> of monolayer phosphorene-based microstructure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1390953','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1390953"><span>Europium Effect on the <span class="hlt">Electron</span> <span class="hlt">Transport</span> in Graphene Ribbons</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bobadilla, Alfredo; Ocola, Leonidas E.; Sumant, Anirudha V.; Kaminski, Michael; Kumar, Narendra; Seminario, Jorge M.</p> <p>2015-10-01</p> <p>We report in this complementary theoretical-experimental work the effect of gating on the election <span class="hlt">transport</span> of grapheme ribbons when exposed to very low concentration of europium in an aqueous solution. We find a direct correlation between the level of concentration of europium ions in the solvent and the change in <span class="hlt">electron</span> <span class="hlt">transport</span> in graphene, observing a change of up to 3 orders of magnitude at the lowest level of concentration tested (0.1 mM), suggesting a possibility that graphene ribbons can be used for detecting very low concentrations of europium in liquid solutions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1096488','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1096488"><span>LDRD project 151362 : low energy <span class="hlt">electron</span>-photon <span class="hlt">transport</span>.</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kensek, Ronald Patrick; Hjalmarson, Harold Paul; Magyar, Rudolph J.; Bondi, Robert James; Crawford, Martin James</p> <p>2013-09-01</p> <p>At sufficiently high energies, the wavelengths of <span class="hlt">electrons</span> and photons are short enough to only interact with one atom at time, leading to the popular %E2%80%9Cindependent-atom approximation%E2%80%9D. We attempted to incorporate atomic structure in the generation of cross sections (which embody the modeled physics) to improve <span class="hlt">transport</span> at lower energies. We document our successes and failures. This was a three-year LDRD project. The core team consisted of a radiation-<span class="hlt">transport</span> expert, a solid-state physicist, and two DFT experts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994PhDT........87K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994PhDT........87K"><span><span class="hlt">Transport</span> Studies in Parallel Two-Dimensional <span class="hlt">Electron</span> Gases</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Katayama, Yasunao</p> <p></p> <p>This thesis presents <span class="hlt">electron</span> <span class="hlt">transport</span> studies in GaAs-AlAs double quantum wells (DQW's) where a system of nearby parallel two-dimensional <span class="hlt">electron</span> gases is formed. It starts from a systematic modeling of the system from a circuit level down to a microscopic quantum mechanical level based on a single <span class="hlt">electron</span> model. A new concept of "virtual separation of node", in which different circuit nodes represent energies at the Fermi level and at the subband edge of the quantum well, enables the hierarchical modeling of the system, significantly reducing the computation time of the transient analysis. Then, two experiments, done in low temperature, demonstrate physics beyond the above framework. The first experiment shows a sudden charge transfer, when the wells are biased, associated with strong inter-layer Coulomb scattering. The other finds a strong temperature dependence of the resonant tunneling between the two wells in contrast to ordinary <span class="hlt">electron</span> tunneling process in metal-insulator-metal junctions or semiconductors. It is argued that the <span class="hlt">electron-electron</span> correlation originating from the small inter-layer <span class="hlt">electron</span> spacing comparable to the intra-layer <span class="hlt">electron</span> spacing is responsible for the former and the interaction with the external phonon bath usually neglected at low temperature for the latter. Finally, a couple of possibilities to make device building blocks out of DQW systems are discussed. In particular, a new type of junction, dubbed SD-junction, which consists of an abrupt interface between double- to single-QW interface, is proposed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Nanot..27m5302S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Nanot..27m5302S"><span>Geometric effects in the <span class="hlt">electronic</span> <span class="hlt">transport</span> of deformed nanotubes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Santos, Fernando; Fumeron, Sébastien; Berche, Bertrand; Moraes, Fernando</p> <p>2016-04-01</p> <p>Quasi-two-dimensional systems may exibit curvature, which adds three-dimensional influence to their internal properties. As shown by da Costa (1981 Phys. Rev. A 23 1982-7), charged particles moving on a curved surface experience a curvature-dependent potential which greatly influence their dynamics. In this paper, we study the <span class="hlt">electronic</span> ballistic <span class="hlt">transport</span> in deformed nanotubes. The one-<span class="hlt">electron</span> Schrödinger equation with open boundary conditions is solved numerically with a flexible MAPLE code made available as supplementary data. We find that the curvature of the deformations indeed has strong effects on the <span class="hlt">electron</span> dynamics, suggesting its use in the design of nanotube-based <span class="hlt">electronic</span> devices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22051363','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22051363"><span>Spatially resolved study of primary <span class="hlt">electron</span> <span class="hlt">transport</span> in magnetic cusps</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hubble, Aimee A.; Foster, John E.</p> <p>2012-01-15</p> <p>Spatially resolved primary <span class="hlt">electron</span> current density profiles were measured using a planar Langmuir probe in the region above a magnetic cusp in a small ion thruster discharge chamber. The probe current maps obtained were used to study the <span class="hlt">electron</span> collection mechanics in the cusp region in the limit of zero gas flow and no plasma production, and they allowed for the visualization of primary <span class="hlt">electron</span> <span class="hlt">transport</span> through the cusp. Attenuation coefficients and loss widths were calculated as a function of probe distance above the anode at various operating conditions. Finally, the collection mechanics between two magnetic cusps were studied and compared. It was found that primary <span class="hlt">electron</span> collection was dominated by the upstream magnet ring.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/3847','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/3847"><span>The macro response Monte Carlo method for <span class="hlt">electron</span> <span class="hlt">transport</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Svatos, M M</p> <p>1998-09-01</p> <p>The main goal of this thesis was to prove the feasibility of basing <span class="hlt">electron</span> depth dose calculations in a phantom on first-principles single scatter physics, in an amount of time that is equal to or better than current <span class="hlt">electron</span> Monte Carlo methods. The Macro Response Monte Carlo (MRMC) method achieves run times that are on the order of conventional <span class="hlt">electron</span> <span class="hlt">transport</span> methods such as condensed history, with the potential to be much faster. This is possible because MRMC is a Local-to-Global method, meaning the problem is broken down into two separate <span class="hlt">transport</span> calculations. The first stage is a local, in this case, single scatter calculation, which generates probability distribution functions (PDFs) to describe the <span class="hlt">electron</span>'s energy, position and trajectory after leaving the local geometry, a small sphere or "kugel" A number of local kugel calculations were run for calcium and carbon, creating a library of kugel data sets over a range of incident energies (0.25 MeV - 8 MeV) and sizes (0.025 cm to 0.1 cm in radius). The second <span class="hlt">transport</span> stage is a global calculation, where steps that conform to the size of the kugels in the library are taken through the global geometry. For each step, the appropriate PDFs from the MRMC library are sampled to determine the <span class="hlt">electron</span>'s new energy, position and trajectory. The <span class="hlt">electron</span> is immediately advanced to the end of the step and then chooses another kugel to sample, which continues until <span class="hlt">transport</span> is completed. The MRMC global stepping code was benchmarked as a series of subroutines inside of the Peregrine Monte Carlo code. It was compared to Peregrine's class II condensed history <span class="hlt">electron</span> <span class="hlt">transport</span> package, EGS4, and MCNP for depth dose in simple phantoms having density inhomogeneities. Since the kugels completed in the library were of relatively small size, the zoning of the phantoms was scaled down from a clinical size, so that the energy deposition algorithms for spreading dose across 5-10 zones per kugel could be tested. Most</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19940000063&hterms=learning+environments&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dlearning%2Benvironments','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19940000063&hterms=learning+environments&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dlearning%2Benvironments"><span><span class="hlt">Transportable</span> Applications <span class="hlt">Environment</span> Plus, Version 5.1</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1994-01-01</p> <p><span class="hlt">Transportable</span> Applications <span class="hlt">Environment</span> Plus (TAE+) computer program providing integrated, portable programming <span class="hlt">environment</span> for developing and running application programs based on interactive windows, text, and graphical objects. Enables both programmers and nonprogrammers to construct own custom application interfaces easily and to move interfaces and application programs to different computers. Used to define corporate user interface, with noticeable improvements in application developer's and end user's learning curves. Main components are; WorkBench, What You See Is What You Get (WYSIWYG) software tool for design and layout of user interface; and WPT (Window Programming Tools) Package, set of callable subroutines controlling user interface of application program. WorkBench and WPT's written in C++, and remaining code written in C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19940000063&hterms=environments+learning&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Denvironments%2Blearning','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19940000063&hterms=environments+learning&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Denvironments%2Blearning"><span><span class="hlt">Transportable</span> Applications <span class="hlt">Environment</span> Plus, Version 5.1</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>1994-01-01</p> <p><span class="hlt">Transportable</span> Applications <span class="hlt">Environment</span> Plus (TAE+) computer program providing integrated, portable programming <span class="hlt">environment</span> for developing and running application programs based on interactive windows, text, and graphical objects. Enables both programmers and nonprogrammers to construct own custom application interfaces easily and to move interfaces and application programs to different computers. Used to define corporate user interface, with noticeable improvements in application developer's and end user's learning curves. Main components are; WorkBench, What You See Is What You Get (WYSIWYG) software tool for design and layout of user interface; and WPT (Window Programming Tools) Package, set of callable subroutines controlling user interface of application program. WorkBench and WPT's written in C++, and remaining code written in C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PSST...26g5003G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PSST...26g5003G"><span>Unified fluid model analysis and benchmark study for <span class="hlt">electron</span> <span class="hlt">transport</span> in gas and liquid analogs</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Garland, N. A.; Cocks, D. G.; Boyle, G. J.; Dujko, S.; White, R. D.</p> <p>2017-07-01</p> <p>The interaction of plasmas with liquids requires an understanding of charged particle <span class="hlt">transport</span> in both the gaseous and liquid phases. In this study we present a generalized fluid-equation framework to describe bulk <span class="hlt">electron</span> <span class="hlt">transport</span> in both gaseous and non-polar liquid <span class="hlt">environments</span> under non-hydrodynamic non-equilibrium conditions. The framework includes liquid structural effects through appropriate inclusion of coherent scattering effects and adaption of swarm data to account for the modification to the scattering <span class="hlt">environment</span> present in such systems. In the limit of low-densities it reduces to the traditional gas-phase fluid-equation model. Using a higher-order fluid model (four moments), it is shown that by applying steady state <span class="hlt">electron</span> swarm data in both the gaseous and liquid phases, to close the system of equations and evaluate collisional rates, an improvement in macroscopic <span class="hlt">electron</span> <span class="hlt">transport</span> results over popular existing assumptions used. The failure of the local mean energy approximation in fluid models to accurately describe complex spatial oscillatory structures in both the gaseous and liquid phases is discussed in terms of the spatial variation of the <span class="hlt">electron</span> distribution function itself.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/503467','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/503467"><span>Fabrication and <span class="hlt">electronic</span> <span class="hlt">transport</span> studies of single nanocrystal systems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Klein, David Louis</p> <p>1997-05-01</p> <p>Semiconductor and metallic nanocrystals exhibit interesting <span class="hlt">electronic</span> <span class="hlt">transport</span> behavior as a result of electrostatic and quantum mechanical confinement effects. These effects can be studied to learn about the nature of <span class="hlt">electronic</span> states in these systems. This thesis describes several techniques for the <span class="hlt">electronic</span> study of nanocrystals. The primary focus is the development of novel methods to attach leads to prefabricated nanocrystals. This is because, while nanocrystals can be readily synthesized from a variety of materials with excellent size control, means to make electrical contact to these nanocrystals are limited. The first approach that will be described uses scanning probe microscopy to first image and then electrically probe surfaces. It is found that <span class="hlt">electronic</span> investigations of nanocrystals by this technique are complicated by tip-sample interactions and environmental factors such as salvation and capillary forces. Next, an atomic force microscope technique for the catalytic patterning of the surface of a self assembled monolayer is described. In principle, this nano-fabrication technique can be used to create <span class="hlt">electronic</span> devices which are based upon complex arrangements of nanocrystals. Finally, the fabrication and electrical characterization of a nanocrystal-based single <span class="hlt">electron</span> transistor is presented. This device is fabricated using a hybrid scheme which combines <span class="hlt">electron</span> beam lithography and wet chemistry to bind single nanocrystals in tunneling contact between closely spaced metallic leads. In these devices, both Au and CdSe nanocrystals show Coulomb blockade effects with characteristic energies of several tens of meV. Additional structure is seen the <span class="hlt">transport</span> behavior of CdSe nanocrystals as a result of its <span class="hlt">electronic</span> structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhRvB..83x1404R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhRvB..83x1404R"><span>Single-<span class="hlt">electron</span> heat diode: Asymmetric heat <span class="hlt">transport</span> between <span class="hlt">electronic</span> reservoirs through Coulomb islands</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruokola, Tomi; Ojanen, Teemu</p> <p>2011-06-01</p> <p>We introduce a functional nanoscale device, a single-<span class="hlt">electron</span> heat diode, consisting of two quantum dots or metallic islands coupled to <span class="hlt">electronic</span> reservoirs by tunnel contacts. <span class="hlt">Electron</span> <span class="hlt">transport</span> through the system is forbidden but the capacitive coupling between the two dots allows <span class="hlt">electronic</span> fluctuations to transmit heat between the reservoirs. When the reservoir temperatures are biased in the forward direction, heat flow is enabled by a four-step sequential tunneling cycle, while in the reverse-biased configuration this process is suppressed due to Coulomb blockade effects. In an optimal setup the leakage heat current in the reverse direction is only a few percent of the forward current.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20860240','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20860240"><span>Nonlocal <span class="hlt">electron</span> <span class="hlt">transport</span> in magnetized plasmas with arbitrary atomic number</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bennaceur-Doumaz, D.; Bendib, A.</p> <p>2006-09-15</p> <p>The numerical solution of the steady-state <span class="hlt">electron</span> Fokker-Planck equation perturbed with respect to a global equilibrium is presented in magnetized plasmas with arbitrary atomic number Z. The magnetic field is assumed to be constant and the <span class="hlt">electron-electron</span> collisions are described by the Landau collision operator. The solution is derived in the Fourier space and in the framework of the diffusive approximation which captures the spatial nonlocal effects. The <span class="hlt">transport</span> coefficients are deduced and used to close a complete set of nonlocal <span class="hlt">electron</span> fluid equations. This work improves the results of A. Bendib et al. [Phys. Plasmas 9, 1555 (2002)] and of A. V. Brantov et al. [Phys. Plasmas 10, 4633 (2003)] restricted to the local and nonlocal high-Z plasma approximations, respectively. The influence of the magnetic field on the nonlocal effects is discussed. We propose also accurate numerical fits of the relevant <span class="hlt">transport</span> coefficients with respect to the collisionality parameter {lambda}{sub ei}/L and the atomic number Z, where L is the typical scale length and {lambda}{sub ei} is the <span class="hlt">electron</span>-ion mean-free-path.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23910074','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23910074"><span>Does menaquinone participate in brain astrocyte <span class="hlt">electron</span> <span class="hlt">transport</span>?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lovern, Douglas; Marbois, Beth</p> <p>2013-10-01</p> <p>Quinone compounds act as membrane resident carriers of <span class="hlt">electrons</span> between components of the <span class="hlt">electron</span> <span class="hlt">transport</span> chain in the periplasmic space of prokaryotes and in the mitochondria of eukaryotes. Vitamin K is a quinone compound in the human body in a storage form as menaquinone (MK); distribution includes regulated amounts in mitochondrial membranes. The human brain, which has low amounts of typical vitamin K dependent function (e.g., gamma carboxylase) has relatively high levels of MK, and different regions of brain have different amounts. Coenzyme Q (Q), is a quinone synthesized de novo, and the levels of synthesis decline with age. The levels of MK are dependent on dietary intake and generally increase with age. MK has a characterized role in the transfer of <span class="hlt">electrons</span> to fumarate in prokaryotes. A newly recognized fumarate cycle has been identified in brain astrocytes. The MK precursor menadione has been shown to donate <span class="hlt">electrons</span> directly to mitochondrial complex III. Vitamin K compounds function in the <span class="hlt">electron</span> <span class="hlt">transport</span> chain of human brain astrocytes. Copyright © 2013 Elsevier Ltd. All rights reserved.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT........89D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT........89D"><span>Quantum <span class="hlt">Transport</span> of <span class="hlt">Electrons</span> through Graphene and Carbon Nanotubes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Das, Shambhu K.</p> <p></p> <p>Quantum <span class="hlt">transport</span> of <span class="hlt">electrons</span> through graphene has attracted increased interest in the field of nano-technology. Quantum <span class="hlt">transport</span> through mesoscopic systems explains a wide range of interesting experimental findings, such as: rectification, switching mechanism and transistor actions. We focused our research on the quantum transmission of <span class="hlt">electrons</span> through graphene and carbon nanotubes. Graphene and nanotube devices operated between source and drain shows a peculiar negative differential resistance behavior (NDR) while drawing current-voltage characteristics. This property is used in many <span class="hlt">electronic</span> devices. The main feature of graphene is that the <span class="hlt">electron</span> has zero effective mass at Dirac points, but gains mass when the graphene sheet is folded into a nanotube. Scientists have analyzed the vanishing mass of the <span class="hlt">electron</span> inside graphene and explain the observed mass gain through Higgs mechanism. We focus our study on the Klein Paradox which deals with the reflection probability greater than one as well as a negative transmission probability. This has been predicted by Oscar Klein and remained a mystery until 1929; the Klein Paradox finally was proven with experimental and theoretical evidence by Geim and Novoselov. In the case of graphene, conductivity is an exponential function of temperature, whereas nanotubes follow a power law. This is a very characteristic feature of quantum dots.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017TDM.....4b5028J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017TDM.....4b5028J"><span><span class="hlt">Electron</span> hopping <span class="hlt">transport</span> in 2D zinc oxide nanoflakes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jian, Dunliang; Lai, Jian-Jhong; Lin, Yen-Fu; Zhai, Jianpang; Li, Irene Ling; Tian, Feng; Wang, Shulin; Hua, Ping; Ku, Ming-Ming; Jian, Wen-Bin; Ruan, Shuangchen; Tang, Zikang</p> <p>2017-06-01</p> <p>A sequential hydrothermal process was used to synthesize ZnO nanostructures on Si substrates. The synthesized ZnO nanostructures were inspected and presented a morphology of 2D structures, named nanoflakes. These ZnO nanoflakes had a thickness of tens of nanometers. An energy dispersive x-ray spectrum revealed their composition of only Zn and O elements. In addition, its crystalline structure was investigated by high-resolution transmission <span class="hlt">electron</span> microscopy. The nanoflakes were then dispersed for another morphology measurement using atomic force microscopy and their average thickness was determined. The dispersed nanoflakes were further contacted with metal electrodes for <span class="hlt">electron</span> <span class="hlt">transport</span> measurements. Through the analysis of temperature-dependent resistivity, it was confirmed that the <span class="hlt">electron</span> <span class="hlt">transport</span> in such ZnO nanoflakes agrees well with the theory of Mott’s 2D variable range hopping. The nature of the 2D <span class="hlt">electron</span> system in the ZnO nanoflakes points to potential applications of this 2D semiconductor as a new channel material for <span class="hlt">electronics</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvB..94l5118W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvB..94l5118W"><span>Interlayer <span class="hlt">electronic</span> <span class="hlt">transport</span> in CaMnBi2 antiferromagnet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Aifeng; Graf, D.; Wu, Lijun; Wang, Kefeng; Bozin, E.; Zhu, Yimei; Petrovic, C.</p> <p>2016-09-01</p> <p>We report interlayer <span class="hlt">electronic</span> <span class="hlt">transport</span> in CaMnBi2 single crystals. Quantum oscillations and angular magnetoresistance suggest coherent <span class="hlt">electronic</span> conduction and valley polarized conduction of Dirac states. The small cyclotron mass, high mobility of carriers, and nontrivial Berry's phase are consistent with the presence of Dirac fermions on the side wall of the warped cylindrical Fermi surface. Similarly to SrMnBi2, which features an anisotropic Dirac cone, our results suggest that magnetic-field-induced changes in interlayer conduction are also present in layered bismuth-based materials with a zero-energy line in momentum space created by the staggered alkaline earth atoms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1345748-interlayer-electronic-transport-camnbi2-antiferromagnet','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1345748-interlayer-electronic-transport-camnbi2-antiferromagnet"><span>Interlayer <span class="hlt">electronic</span> <span class="hlt">transport</span> in CaMnBi2 antiferromagnet</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Wang, Aifeng; Graf, D.; Wu, Lijun; ...</p> <p>2016-09-12</p> <p>Here, we report interlayer <span class="hlt">electronic</span> <span class="hlt">transport</span> in CaMnBi2 single crystals. Quantum oscillations and angular magnetoresistance suggest coherent <span class="hlt">electronic</span> conduction and valley polarized conduction of Dirac states. Furthermore, the small cyclotron mass, high mobility of carriers, and nontrivial Berry's phase are consistent with the presence of Dirac fermions on the side wall of the warped cylindrical Fermi surface. Similarly to SrMnBi2 , which features an anisotropic Dirac cone, our results suggest that magnetic-field-induced changes in interlayer conduction are also present in layered bismuth-based materials with a zero-energy line in momentum space created by the staggered alkaline earth atoms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhD...50w4005A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhD...50w4005A"><span><span class="hlt">Electron</span> and phonon <span class="hlt">transport</span> in twisted graphene nanoribbons</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Antidormi, Aleandro; Royo, Miquel; Rurali, Riccardo</p> <p>2017-06-01</p> <p>We theoretically study the <span class="hlt">electronic</span>, thermal and thermoelectric properties of graphene nanoribbons under torsional deformations. The modelling follows a nonequilibrium Green’s function approach in the ballistic <span class="hlt">transport</span> regime, describing the electrical and phononic properties through ab initio density functional theory and empirical interatomic potentials, respectively. We consider two different types of deformations, a continuous twist of a given angle applied to the nanoribbon, and two consecutive twists applied in opposite angular directions. The numerical results are carefully analysed in terms of spatially-resolved <span class="hlt">electron</span> eigenchannels, polarization-dependent phonon transmission and thermoelectric figure-of-merit.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://files.eric.ed.gov/fulltext/ED299450.pdf','ERIC'); return false;" href="http://files.eric.ed.gov/fulltext/ED299450.pdf"><span>Sherlock: A Coached Practice <span class="hlt">Environment</span> for an <span class="hlt">Electronics</span> Troubleshooting Job.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Lesgold, Alan; And Others</p> <p></p> <p>"Sherlock" is a computer-based, supported practice <span class="hlt">environment</span> for a complex troubleshooting job in Air Force <span class="hlt">electronics</span>. The program was developed to raise the level of troubleshooting knowledge of avionics technicians. This describes the training problem for which Sherlock was developed, the principles behind its development, and its…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=digital+AND+electronics&pg=7&id=EJ989538','ERIC'); return false;" href="http://eric.ed.gov/?q=digital+AND+electronics&pg=7&id=EJ989538"><span>Expression and Association Rights of School Employees in <span class="hlt">Electronic</span> <span class="hlt">Environments</span></span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Bathon, Justin M.</p> <p>2012-01-01</p> <p>Many of the recent legal decisions regarding public employee expression, particularly in <span class="hlt">electronic</span> <span class="hlt">environments</span>, run counter to the culture being facilitated by the Internet. This article uses a legal analysis to examine recent decisions and then considers those legal positions within the context of digital expression. (Contains 2 notes.)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=run&pg=7&id=EJ989538','ERIC'); return false;" href="https://eric.ed.gov/?q=run&pg=7&id=EJ989538"><span>Expression and Association Rights of School Employees in <span class="hlt">Electronic</span> <span class="hlt">Environments</span></span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Bathon, Justin M.</p> <p>2012-01-01</p> <p>Many of the recent legal decisions regarding public employee expression, particularly in <span class="hlt">electronic</span> <span class="hlt">environments</span>, run counter to the culture being facilitated by the Internet. This article uses a legal analysis to examine recent decisions and then considers those legal positions within the context of digital expression. (Contains 2 notes.)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatCo...711381B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatCo...711381B"><span>Nanoscale <span class="hlt">electron</span> <span class="hlt">transport</span> at the surface of a topological insulator</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bauer, Sebastian; Bobisch, Christian A.</p> <p>2016-04-01</p> <p>The use of three-dimensional topological insulators for disruptive technologies critically depends on the dissipationless <span class="hlt">transport</span> of <span class="hlt">electrons</span> at the surface, because of the suppression of backscattering at defects. However, in real devices, defects are unavoidable and scattering at angles other than 180° is allowed for such materials. Until now, this has been studied indirectly by bulk measurements and by the analysis of the local density of states in close vicinity to defect sites. Here, we directly measure the nanoscale voltage drop caused by the scattering at step edges, which occurs if a lateral current flows along a three-dimensional topological insulator. The experiments were performed using scanning tunnelling potentiometry for thin Bi2Se3 films. So far, the observed voltage drops are small because of large contributions of the bulk to the <span class="hlt">electronic</span> <span class="hlt">transport</span>. However, for the use of ideal topological insulating thin films in devices, these contributions would play a significant role.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21537874','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21537874"><span><span class="hlt">Electron</span> heat <span class="hlt">transport</span> from stochastic fields in gyrokinetic simulations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wang, E.; Nevins, W. M.; Candy, J.; Hatch, D.; Terry, P.; Guttenfelder, W.</p> <p>2011-05-15</p> <p>GYRO is used to examine the perturbed magnetic field structure generated by electromagnetic gyrokinetic simulations of the CYCLONE base case as {beta}{sub e} is varied from 0.1% to 0.7%, as investigated by J. Candy [Phys. Plasmas 12, 072307 (2005)]. Poincare surface of section plots obtained from integrating the self-consistent magnetic field demonstrates widespread stochasticity for all nonzero values of {beta}{sub e}. Despite widespread stochasticity of the perturbed magnetic fields, no significant increase in <span class="hlt">electron</span> <span class="hlt">transport</span> is observed. The magnetic diffusion, d{sub m}[A. B. Rechester and M. N. Rosenbluth, Phys. Rev. Lett 40, 38 (1978)], is used to quantify the degree of stochasticity and related to the <span class="hlt">electron</span> heat <span class="hlt">transport</span> for hundreds of time slices in each simulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhPl...18e6111W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhPl...18e6111W"><span><span class="hlt">Electron</span> heat <span class="hlt">transport</span> from stochastic fields in gyrokinetic simulationsa)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, E.; Nevins, W. M.; Candy, J.; Hatch, D.; Terry, P.; Guttenfelder, W.</p> <p>2011-05-01</p> <p>GYRO is used to examine the perturbed magnetic field structure generated by electromagnetic gyrokinetic simulations of the CYCLONE base case as βe is varied from 0.1% to 0.7%, as investigated by J. Candy [Phys. Plasmas 12, 072307 (2005)]. Poincare surface of section plots obtained from integrating the self-consistent magnetic field demonstrates widespread stochasticity for all nonzero values of βe. Despite widespread stochasticity of the perturbed magnetic fields, no significant increase in <span class="hlt">electron</span> <span class="hlt">transport</span> is observed. The magnetic diffusion, dm [A. B. Rechester and M. N. Rosenbluth, Phys. Rev. Lett 40, 38 (1978)], is used to quantify the degree of stochasticity and related to the <span class="hlt">electron</span> heat <span class="hlt">transport</span> for hundreds of time slices in each simulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28745878','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28745878"><span><span class="hlt">Electronic</span> <span class="hlt">Transport</span> in Bilayer MoS2 Encapsulated in HfO2.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Matis, Bernard R; Garces, Nelson Y; Cleveland, Erin R; Houston, Brian H; Baldwin, Jeffrey W</p> <p>2017-08-23</p> <p>The exact nature of the interface between a two-dimensional crystal and its <span class="hlt">environment</span> can have a significant impact on the <span class="hlt">electronic</span> <span class="hlt">transport</span> within the crystal, and can place fundamental limitations on transistor performance and long-term functionality. Two-dimensional transition-metal dichalcogenides are a new class of transistor channel material with <span class="hlt">electronic</span> properties that can be tailored through dielectric engineering of the material/environmental interface. Here, we report electrical <span class="hlt">transport</span> measurements carried out in the insulating regime of bilayer molybdenum disulfide, which has been encapsulated within a high-κ hafnium oxide dielectric. Temperature- and carrier-density-dependent measurements show that for T < 130 K the <span class="hlt">transport</span> is governed by resonant tunneling, and at T = 4.2 K the tunneling peak lineshape is well-fitted by a Lorentzian with an amplitude less than e(2)/h. Estimates of tunneling time give τ ∼ 1.2 ps corresponding to a frequency f ∼ 0.84 THz. The tunneling processes are observable up to T ∼ 190 K (more than a factor of 6 higher than that previously reported for MoS2 on SiO2) despite the onset of variable range hopping at T ∼ 130 K, demonstrating the coexistence of the two <span class="hlt">transport</span> processes within the same temperature range. At constant temperature, varying the Fermi energy allows experimental access to each <span class="hlt">transport</span> process. The results are interpreted in terms of an increase in charge carrier screening length and a decrease in <span class="hlt">electron</span>-phonon coupling induced by the hafnium oxide. Our results represent the first demonstration of the intermediate tunneling-hopping <span class="hlt">transport</span> regime in a two-dimensional material. The results suggest that interface engineering may be a macroscopic tool for controlling quantum <span class="hlt">transport</span> within such materials as well as for increasing the operating temperatures for resonant-tunneling devices derived from such materials, with applications in high-frequency <span class="hlt">electronics</span> and logic devices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=246107','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=246107"><span>Lipophilic chelator inhibition of <span class="hlt">electron</span> <span class="hlt">transport</span> in Escherichia coli.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Crane, R T; Sun, I L; Crane, F L</p> <p>1975-01-01</p> <p>The lipophilic chelator bathophenanthroline inhibits <span class="hlt">electron</span> <span class="hlt">transport</span> in membranes from Escherichia coli. The less lipophilic 1,10-phenanthroline, bathophenanthroline sulfonate, and alpha,alpha-dipyridyl have little effect. Reduced nicotinamide adenine dinucleotide oxidase is more sensitive to bathophenanthroline inhibition than lactate oxidase activity. Evidence for two sites of inhibition comes from the fact that both reduced nicotinamide adenine dinucleotide menadione reductase and duroquinol oxidase activities are inhibited. Addition of uncouplers of phosphorylation before bathophenanthroline protects against inhibition. PMID:1092663</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006CP....326..138X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006CP....326..138X"><span>Redox-gated <span class="hlt">electron</span> <span class="hlt">transport</span> in electrically wired ferrocene molecules</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiao, Xiaoyin; Brune, Daniel; He, Jin; Lindsay, Stuart; Gorman, Christopher B.; Tao, Nongjian</p> <p>2006-07-01</p> <p>We have synthesized cysteamine-terminated ferrocene molecules and determined the dependence of the <span class="hlt">electron</span> <span class="hlt">transport</span> properties of the molecules on their redox states by measuring the current through the molecules as a function of the electrode potential. The current fluctuates over a large range, but its average value increases with the potential. We attribute the current fluctuation and its increase with the potential to the switching of the molecules from low-conductance reduced state to high-conductance oxidized state.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24302213','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24302213"><span>Graphene nanopores: <span class="hlt">electronic</span> <span class="hlt">transport</span> properties and design methodology.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Qiu, Wanzhi; Nguyen, Phuong; Skafidas, Efstratios</p> <p>2014-01-28</p> <p>Graphene nanopores (GNPs) hold great promise as building blocks for <span class="hlt">electronic</span> circuitry and sensors for biological and chemical sensing applications. Methods to design graphene nanopores that achieve desirable conduction performance and sensing characteristics have not been previously described. Here we present a study of the quantum <span class="hlt">transport</span> properties of GNPs created by drilling pores in armchair and zigzag graphene ribbons. For the first time, our study reveals that the quantum transmission spectra of GNPs are highly tunable and GNPs with specific <span class="hlt">transport</span> properties can be produced by properly designing pore shapes. Our investigation shows that the biological sensing capabilities of GNPs are transmission spectrum dependent, can vary dramatically, and are critically dependent on pore geometry. Our study provides design guidelines for creating graphene nanopores with specific <span class="hlt">transport</span> properties to meet the needs of diverse applications and for developing sensitive biological/chemical sensors with required performance characteristics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22493833','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22493833"><span><span class="hlt">Transport</span> of solar <span class="hlt">electrons</span> in the turbulent interplanetary magnetic field</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ablaßmayer, J.; Tautz, R. C.; Dresing, N.</p> <p>2016-01-15</p> <p>The turbulent <span class="hlt">transport</span> of solar energetic <span class="hlt">electrons</span> in the interplanetary magnetic field is investigated by means of a test-particle Monte-Carlo simulation. The magnetic fields are modeled as a combination of the Parker field and a turbulent component. In combination with the direct calculation of diffusion coefficients via the mean-square displacements, this approach allows one to analyze the effect of the initial ballistic <span class="hlt">transport</span> phase. In that sense, the model complements the main other approach in which a <span class="hlt">transport</span> equation is solved. The major advancement is that, by recording the flux of particles arriving at virtual detectors, intensity and anisotropy-time profiles can be obtained. Observational indications for a longitudinal asymmetry can thus be explained by tracing the diffusive spread of the particle distribution. The approach may be of future help for the systematic interpretation of observations for instance by the solar terrestrial relations observatory (STEREO) and advanced composition explorer (ACE) spacecrafts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15093116','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15093116"><span>Modelling radionuclide distribution and <span class="hlt">transport</span> in the <span class="hlt">environment</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thiessen, K M; Thorne, M C; Maul, P R; Pröhl, G; Wheater, H S</p> <p>1999-01-01</p> <p>Mathematical models of radionuclide distribution and <span class="hlt">transport</span> in the <span class="hlt">environment</span> have been developed to assess the impact on people of routine and accidental releases of radioactivity from a variety of nuclear activities, including: weapons development, production, and testing; power production; and waste disposal. The models are used to estimate human exposures and doses in situations where measurements have not been made or would be impossible or impractical to make. Model results are used to assess whether nuclear facilities are operated in compliance with regulatory requirements, to determine the need for remediation of contaminated sites, to estimate the effects on human health of past releases, and to predict the potential effects of accidental releases or new facilities. This paper describes the various applications and types of models currently used to represent the distribution and <span class="hlt">transport</span> of radionuclides in the terrestrial and aquatic <span class="hlt">environments</span>, as well as integrated global models for selected radionuclides and special issues in the fields of solid radioactive waste disposal and dose reconstruction. Particular emphasis is placed on the issue of improving confidence in the model results, including the importance of uncertainty analysis and of model verification and validation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22579359','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22579359"><span>Salicylic acid may indirectly influence the photosynthetic <span class="hlt">electron</span> <span class="hlt">transport</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Janda, Katalin; Hideg, Eva; Szalai, Gabriella; Kovács, László; Janda, Tibor</p> <p>2012-07-01</p> <p>Salicylic acid (SA) is a phenolic phytohormone with important roles in plant development, transpiration, endogenous signaling and defense against pathogens. One of the pathways of SA biosynthesis is located in the chloroplasts. The aim of the present work was to investigate the possible regulatory effects of SA on photosynthetic <span class="hlt">electron</span> <span class="hlt">transport</span> processes. Here we show that SA also affects leaf photosynthesis, via inducing stomatal closure and also by slowing down Photosystem II (PS II) <span class="hlt">electron</span> <span class="hlt">transport</span>. Photosynthetic CO₂ incorporation and stomatal conductivity (measured with an infrared gas analyzer) were much lower in SA-infiltrated tobacco leaves than in untreated or water-infiltrated controls. PS II <span class="hlt">electron</span> <span class="hlt">transport</span> (calculated from PAM chlorophyll fluorescence data) was more sensitive to SA than Photosystem I (PS I) (measured with far red absorption). Direct probing of PS II charge separation and stabilization (measured with thermoluminescence), however, showed that these events were less affected in isolated thylakoid membranes than in leaves, suggesting that the effect of SA on PS II is indirect and different from similar effects of phenolic herbicides. Copyright © 2012 Elsevier GmbH. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/598594','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/598594"><span>Modeling <span class="hlt">electron</span> heat <span class="hlt">transport</span> during magnetic field buildup in SSPX</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hua, D.D.; Hooper, E.B.; Fowler, T.K.</p> <p>1997-10-01</p> <p>A model for spheromak magnetic field buildup and <span class="hlt">electron</span> thermal <span class="hlt">transport</span>, including a thermal diffusivity associated with magnetic turbulence during helicity injection is applied to a SSPX equilibrium, with a maximum final magnetic field of 1.3 T. Magnetic field-buildup times of 1.0 X 10-3, 5.0 X 10-4 and 1.0 X 10-4 s were used in the model to examine their effects on <span class="hlt">electron</span> thermal <span class="hlt">transport</span>. It is found that at <span class="hlt">transport</span> run time of 4 x 10-3 s, the fastest buildup-time results in the highest final temperature profile, with a core temperature of 0.93 kev while requiring the lowest input energy at 140 KJ. The results show that within the model the most rapid buildup rate generates the highest <span class="hlt">electron</span> temperature at the fastest rate and at the lowest consumption of energy. However, the peak power requirements are large (> 600 MW for the fastest buildup case examined).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013Nanot..24i5701M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013Nanot..24i5701M"><span><span class="hlt">Electron</span> <span class="hlt">transport</span> in gold colloidal nanoparticle-based strain gauges</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moreira, Helena; Grisolia, Jérémie; Sangeetha, Neralagatta M.; Decorde, Nicolas; Farcau, Cosmin; Viallet, Benoit; Chen, Ke; Viau, Guillaume; Ressier, Laurence</p> <p>2013-03-01</p> <p>A systematic approach for understanding the <span class="hlt">electron</span> <span class="hlt">transport</span> mechanisms in resistive strain gauges based on assemblies of gold colloidal nanoparticles (NPs) protected by organic ligands is described. The strain gauges were fabricated from parallel micrometer wide wires made of 14 nm gold (Au) colloidal NPs on polyethylene terephthalate substrates, elaborated by convective self-assembly. <span class="hlt">Electron</span> <span class="hlt">transport</span> in such devices occurs by inter-particle <span class="hlt">electron</span> tunneling through the tunnel barrier imposed by the organic ligands protecting the NPs. This tunnel barrier was varied by changing the nature of organic ligands coating the nanoparticles: citrate (CIT), phosphines (BSPP, TDSP) and thiols (MPA, MUDA). Electro-mechanical tests indicate that only the gold NPs protected by phosphine and thiol ligands yield high gauge sensitivity. Temperature-dependent resistance measurements are explained using the ‘regular island array model’ that extracts <span class="hlt">transport</span> parameters, i.e., the tunneling decay constant β and the Coulomb charging energy EC. This reveals that the Au@CIT nanoparticle assemblies exhibit a behavior characteristic of a strong-coupling regime, whereas those of Au@BSPP, Au@TDSP, Au@MPA and Au@MUDA nanoparticles manifest a weak-coupling regime. A comparison of the parameters extracted from the two methods indicates that the most sensitive gauges in the weak-coupling regime feature the highest β. Moreover, the EC values of these 14 nm NPs cannot be neglected in determining the β values.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5422172','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5422172"><span>Detecting <span class="hlt">Electron</span> <span class="hlt">Transport</span> of Amino Acids by Using Conductance Measurement</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Li, Wei-Qiong; Huang, Bing; Huang, Miao-Ling; Peng, Lin-Lu; Hong, Ze-Wen; Zheng, Ju-Fang; Chen, Wen-Bo; Li, Jian-Feng; Zhou, Xiao-Shun</p> <p>2017-01-01</p> <p>The single molecular conductance of amino acids was measured by a scanning tunneling microscope (STM) break junction. Conductance measurement of alanine gives out two conductance values at 10−1.85 G0 (1095 nS) and 10−3.7 G0 (15.5 nS), while similar conductance values are also observed for aspartic acid and glutamic acid, which have one more carboxylic acid group compared with alanine. This may show that the backbone of NH2–C–COOH is the primary means of <span class="hlt">electron</span> <span class="hlt">transport</span> in the molecular junction of aspartic acid and glutamic acid. However, NH2–C–COOH is not the primary means of <span class="hlt">electron</span> <span class="hlt">transport</span> in the methionine junction, which may be caused by the strong interaction of the Au–SMe (methyl sulfide) bond for the methionine junction. The current work reveals the important role of the anchoring group in the <span class="hlt">electron</span> <span class="hlt">transport</span> in different amino acids junctions. PMID:28394265</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20010055260','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20010055260"><span>Low Energy <span class="hlt">Electrons</span> in the Mars Plasma <span class="hlt">Environment</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Link, Richard</p> <p>2001-01-01</p> <p>The ionosphere of Mars is rather poorly understood. The only direct measurements were performed by the Viking 1 and 2 landers in 1976, both of which carried a Retarding Potential Analyzer. The RPA was designed to measure ion properties during the descent, although <span class="hlt">electron</span> fluxes were estimated from changes in the ion currents. Using these derived low-energy <span class="hlt">electron</span> fluxes, Mantas and Hanson studied the photoelectron and the solar wind <span class="hlt">electron</span> interactions with the atmosphere and ionosphere of Mars. Unanswered questions remain regarding the origin of the low-energy <span class="hlt">electron</span> fluxes in the vicinity of the Mars plasma boundary. Crider, in an analysis of Mars Global Surveyor Magnetometer/<span class="hlt">Electron</span> Reflectometer measurements, has attributed the formation of the magnetic pile-up boundary to <span class="hlt">electron</span> impact ionization of exospheric neutral species by solar wind <span class="hlt">electrons</span>. However, the role of photoelectrons escaping from the lower ionosphere was not determined. In the proposed work, we will examine the role of solar wind and ionospheric photoelectrons in producing ionization in the upper ionosphere of Mars. Low-energy (< 4 keV) <span class="hlt">electrons</span> will be modeled using the two-stream <span class="hlt">electron</span> <span class="hlt">transport</span> code of Link. The code models both external (solar wind) and internal (photoelectron) sources of ionization, and accounts for Auger <span class="hlt">electron</span> production. The code will be used to analyze Mars Global Surveyor measurements of solar wind and photoelectrons down to altitudes below 200 km in the Mars ionosphere, in order to determine the relative roles of solar wind and escaping photoelectrons in maintaining plasma densities in the region of the Mars plasma boundary.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22415564','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22415564"><span>The role of <span class="hlt">electron</span>-impact vibrational excitation in <span class="hlt">electron</span> <span class="hlt">transport</span> through gaseous tetrahydrofuran</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Duque, H. V.; Do, T. P. T.; Konovalov, D. A.; White, R. D.; Brunger, M. J. E-mail: darryl.jones@flinders.edu.au; Jones, D. B. E-mail: darryl.jones@flinders.edu.au</p> <p>2015-03-28</p> <p>In this paper, we report newly derived integral cross sections (ICSs) for <span class="hlt">electron</span> impact vibrational excitation of tetrahydrofuran (THF) at intermediate impact energies. These cross sections extend the currently available data from 20 to 50 eV. Further, they indicate that the previously recommended THF ICS set [Garland et al., Phys. Rev. A 88, 062712 (2013)] underestimated the strength of the <span class="hlt">electron</span>-impact vibrational excitation processes. Thus, that recommended vibrational cross section set is revised to address those deficiencies. <span class="hlt">Electron</span> swarm <span class="hlt">transport</span> properties were calculated with the amended vibrational cross section set, to quantify the role of <span class="hlt">electron</span>-driven vibrational excitation in describing the macroscopic swarm phenomena. Here, significant differences of up to 17% in the <span class="hlt">transport</span> coefficients were observed between the calculations performed using the original and revised cross section sets for vibrational excitation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ITNS...64.2016T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ITNS...64.2016T"><span>High-Energy <span class="hlt">Electron</span>-Induced SEUs and Jovian <span class="hlt">Environment</span> Impact</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tali, Maris; Alía, Rubén García; Brugger, Markus; Ferlet-Cavrois, Veronique; Corsini, Roberto; Farabolini, Wilfrid; Mohammadzadeh, Ali; Santin, Giovanni; Virtanen, Ari</p> <p>2017-08-01</p> <p>We present experimental evidence of <span class="hlt">electron</span>-induced upsets in a reference European Space Agency (ESA) single event upset (SEU) monitor, induced by a 200-MeV <span class="hlt">electron</span> beam at the Very energetic <span class="hlt">Electronic</span> facility for Space Planetary Exploration in harsh Radiation <span class="hlt">environments</span> facility at CERN. Comparison of experimental cross sections and simulated cross sections is shown and the differences are analyzed. Possible secondary contributions to the upset rate by neutrons, flash effects, and cumulative dose effects are discussed, showing that electronuclear reactions are the expected SEU mechanism. The ESA Jupiter Icy Moons Explorer mission, to be launched in 2022, presents a challenging radiation <span class="hlt">environment</span> due to the intense high-energy <span class="hlt">electron</span> flux in the trapped radiation belts. Insight is given to the possible contribution of <span class="hlt">electrons</span> to the overall upset rates in the Jovian radiation <span class="hlt">environment</span>. Relative contributions of both typical <span class="hlt">electron</span> and proton spectra created when the environmental spectra are <span class="hlt">transported</span> through a typical spacecraft shielding are shown and the different mission phases are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22486307','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22486307"><span><span class="hlt">Electronic</span> <span class="hlt">transport</span> in VO{sub 2}—Experimentally calibrated Boltzmann <span class="hlt">transport</span> modeling</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kinaci, Alper; Rosenmann, Daniel; Chan, Maria K. Y. E-mail: mchan@anl.gov; Kado, Motohisa; Ling, Chen; Zhu, Gaohua; Banerjee, Debasish E-mail: mchan@anl.gov</p> <p>2015-12-28</p> <p>Materials that undergo metal-insulator transitions (MITs) are under intense study, because the transition is scientifically fascinating and technologically promising for various applications. Among these materials, VO{sub 2} has served as a prototype due to its favorable transition temperature. While the physical underpinnings of the transition have been heavily investigated experimentally and computationally, quantitative modeling of <span class="hlt">electronic</span> <span class="hlt">transport</span> in the two phases has yet to be undertaken. In this work, we establish a density-functional-theory (DFT)-based approach with Hubbard U correction (DFT + U) to model <span class="hlt">electronic</span> <span class="hlt">transport</span> properties in VO{sub 2} in the semiconducting and metallic regimes, focusing on band <span class="hlt">transport</span> using the Boltzmann <span class="hlt">transport</span> equations. We synthesized high quality VO{sub 2} films and measured the <span class="hlt">transport</span> quantities across the transition, in order to calibrate the free parameters in the model. We find that the experimental calibration of the Hubbard correction term can efficiently and adequately model the metallic and semiconducting phases, allowing for further computational design of MIT materials for desirable <span class="hlt">transport</span> properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007PhDT.......149T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007PhDT.......149T"><span>Charge <span class="hlt">transport</span> and injection in amorphous organic <span class="hlt">electronic</span> materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tse, Shing Chi</p> <p></p> <p>This thesis presents how we use various measuring techniques to study the charge <span class="hlt">transport</span> and injection in organic <span class="hlt">electronic</span> materials. Understanding charge <span class="hlt">transport</span> and injection properties in organic solids is of vital importance for improving performance characteristics of organic <span class="hlt">electronic</span> devices, including organic-light-emitting diodes (OLEDs), photovoltaic cells (OPVs), and field effect transistors (OFETs). The charge <span class="hlt">transport</span> properties of amorphous organic materials, commonly used in organic <span class="hlt">electronic</span> devices, are investigated by the means of carrier mobility measurements. Transient electroluminescence (EL) technique was used to evaluate the <span class="hlt">electron</span> mobility of an <span class="hlt">electron</span> <span class="hlt">transporting</span> material--- tris(8-hydroxyquinoline) aluminum (Alq3). The results are in excellent agreement with independent time-of-flight (TOF) measurements. Then, the effect of dopants on <span class="hlt">electron</span> <span class="hlt">transport</span> was also examined. TOF technique was also used to examine the effects of tertiary-butyl (t-Bu) substitutions on anthracene derivatives (ADN). All ADN compounds were found to be ambipolar. As the degree of t-Bu substitution increases, the carrier mobilities decrease progressively. The reduction of carrier mobilities with increasing t-butylation can be attributed to a decrease in the charge-transfer integral or the wavefunction overlap. In addition, from TOF measurements, two naphthylamine-based hole <span class="hlt">transporters</span>, namely, N,N'-diphenyl-N,N'-bis(1-naphthyl)(1,1'-biphenyl)-4,4'diamine (NPB) and 4,4',4"-tris(n-(2-naphthyl)-n-phenyl-amino)-triphenylamine (2TNATA) were found to possess <span class="hlt">electron-transporting</span> (ET) abilities. An organic light-emitting diode that employed NPB as the ET material was demonstrated. The <span class="hlt">electron</span> conducting mechanism of NPB and 2TNATA in relation to the hopping model will be discussed. Furthermore, the ET property of NPB applied in OLEDs will also be examined. Besides transient EL and TOF techniques, we also use dark-injection space-charge-limited current</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25909689','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25909689"><span>Theoretical investigations into the <span class="hlt">electronic</span> structures and <span class="hlt">electron</span> <span class="hlt">transport</span> properties of fluorine and carbonyl end-functionalized quarterthiophenes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Qian; Duan, Yuai; Gao, Hong-Ze; Su, Zhong-Мin; Geng, Yun</p> <p>2015-06-01</p> <p>In this work, we concentrate on systematic investigation on the fluorination and carbonylation effect on <span class="hlt">electron</span> <span class="hlt">transport</span> properties of thiophene-based materials with the aim of seeking and designing <span class="hlt">electron</span> <span class="hlt">transport</span> materials. Some relative factors, namely, frontier molecular orbital (FMO), vertical <span class="hlt">electron</span> affinity (VEA), <span class="hlt">electron</span> reorganization energy (λele), <span class="hlt">electron</span> transfer integral (tele), <span class="hlt">electron</span> drift mobility (μele) and band structures have been calculated and discussed based on density functional theory. The results show that the introduction of fluorine atoms and carbonyl group especially for the latter could effectively increase EA and reduce λele, which is beneficial to the improvement of <span class="hlt">electron</span> <span class="hlt">transport</span> performance. Furthermore, these introductions could also affect the tele by changing molecular packing manner and distribution of FMO. Finally, according to our calculation, the 3d system is considered to be a promising <span class="hlt">electron</span> <span class="hlt">transport</span> material with small λele, high <span class="hlt">electron</span> <span class="hlt">transport</span> ability and good ambient stability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014NatSR...4E5983J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014NatSR...4E5983J"><span>Energy level control: toward an efficient hot <span class="hlt">electron</span> <span class="hlt">transport</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jin, Xiao; Li, Qinghua; Li, Yue; Chen, Zihan; Wei, Tai-Huei; He, Xingdao; Sun, Weifu</p> <p>2014-08-01</p> <p>Highly efficient hot <span class="hlt">electron</span> <span class="hlt">transport</span> represents one of the most important properties required for applications in photovoltaic devices. Whereas the fabrication of efficient hot <span class="hlt">electron</span> capture and lost-cost devices remains a technological challenge, regulating the energy level of acceptor-donor system through the incorporation of foreign ions using the solution-processed technique is one of the most promising strategies to overcome this obstacle. Here we present a versatile acceptor-donor system by incorporating MoO3:Eu nanophosphors, which reduces both the `excess' energy offset between the conduction band of acceptor and the lowest unoccupied molecular orbital of donor, and that between the valence band and highest occupied molecular orbital. Strikingly, the hot <span class="hlt">electron</span> transfer time has been shortened. This work demonstrates that suitable energy level alignment can be tuned to gain the higher hot <span class="hlt">electron</span>/hole <span class="hlt">transport</span> efficiency in a simple approach without the need for complicated architectures. This work builds up the foundation of engineering building blocks for third-generation solar cells.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4124467','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4124467"><span>Energy level control: toward an efficient hot <span class="hlt">electron</span> <span class="hlt">transport</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Jin, Xiao; Li, Qinghua; Li, Yue; Chen, Zihan; Wei, Tai-Huei; He, Xingdao; Sun, Weifu</p> <p>2014-01-01</p> <p>Highly efficient hot <span class="hlt">electron</span> <span class="hlt">transport</span> represents one of the most important properties required for applications in photovoltaic devices. Whereas the fabrication of efficient hot <span class="hlt">electron</span> capture and lost-cost devices remains a technological challenge, regulating the energy level of acceptor-donor system through the incorporation of foreign ions using the solution-processed technique is one of the most promising strategies to overcome this obstacle. Here we present a versatile acceptor-donor system by incorporating MoO3:Eu nanophosphors, which reduces both the ‘excess' energy offset between the conduction band of acceptor and the lowest unoccupied molecular orbital of donor, and that between the valence band and highest occupied molecular orbital. Strikingly, the hot <span class="hlt">electron</span> transfer time has been shortened. This work demonstrates that suitable energy level alignment can be tuned to gain the higher hot <span class="hlt">electron</span>/hole <span class="hlt">transport</span> efficiency in a simple approach without the need for complicated architectures. This work builds up the foundation of engineering building blocks for third-generation solar cells. PMID:25099864</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25099864','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25099864"><span>Energy level control: toward an efficient hot <span class="hlt">electron</span> <span class="hlt">transport</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jin, Xiao; Li, Qinghua; Li, Yue; Chen, Zihan; Wei, Tai-Huei; He, Xingdao; Sun, Weifu</p> <p>2014-08-07</p> <p>Highly efficient hot <span class="hlt">electron</span> <span class="hlt">transport</span> represents one of the most important properties required for applications in photovoltaic devices. Whereas the fabrication of efficient hot <span class="hlt">electron</span> capture and lost-cost devices remains a technological challenge, regulating the energy level of acceptor-donor system through the incorporation of foreign ions using the solution-processed technique is one of the most promising strategies to overcome this obstacle. Here we present a versatile acceptor-donor system by incorporating MoO3:Eu nanophosphors, which reduces both the 'excess' energy offset between the conduction band of acceptor and the lowest unoccupied molecular orbital of donor, and that between the valence band and highest occupied molecular orbital. Strikingly, the hot <span class="hlt">electron</span> transfer time has been shortened. This work demonstrates that suitable energy level alignment can be tuned to gain the higher hot <span class="hlt">electron</span>/hole <span class="hlt">transport</span> efficiency in a simple approach without the need for complicated architectures. This work builds up the foundation of engineering building blocks for third-generation solar cells.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EPJB...90...67A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EPJB...90...67A"><span>Single-<span class="hlt">electron</span> <span class="hlt">transport</span> through quantum point contact</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Akyüz, Gönül Bilgeç; Siddiki, Afif</p> <p>2017-04-01</p> <p>Here, we employ a numerical approach to investigate the <span class="hlt">transport</span> and conductance characteristics of a quantum point contact. A quantum point contact is a narrow constriction of a width comparable to the <span class="hlt">electron</span> wavelength defined in a two-dimensional <span class="hlt">electron</span> gas (2DEG) by means of split-gate or etching technique. Their properties have been widely investigated in the experiments. In our study, we define a quantum Hall based split-gate quantum point contact with standard gate geometry. Firstly, we obtain the spatial distribution of incompressible strips (current channels) by applying a self consistent Thomas-Fermi method to a realistic heterostructure under quantized Hall conditions. Later, time-dependent Schrödinger equation is solved for <span class="hlt">electrons</span> injected in the current channels. The <span class="hlt">transport</span> characteristics and time-evolutions are analyzed in the integer filling factor regime (ν = 1) with the single <span class="hlt">electron</span> density. The results confirm that the current direction in a realistic quantum point contact can be controllable with the external interventions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23173952','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23173952"><span><span class="hlt">Electron</span> <span class="hlt">transport</span> in a GaPSb film.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lo, Shun-Tsung; Lin, Hung En; Wang, Shu-Wei; Lin, Huang-De; Chin, Yu-Chung; Lin, Hao-Hsiung; Lin, Jheng-Cyuan; Liang, Chi-Te</p> <p>2012-11-23</p> <p>We have performed <span class="hlt">transport</span> measurements on a gallium phosphide antimonide (GaPSb) film grown on GaAs. At low temperatures (T), <span class="hlt">transport</span> is governed by three-dimensional Mott variable range hopping (VRH) due to strong localization. Therefore, <span class="hlt">electron-electron</span> interactions are not significant in GaPSb. With increasing T, the coexistence of VRH conduction and the activated behavior with a gap of 20 meV is found. The fact that the measured gap is comparable to the thermal broadening at room temperature (approximately 25 meV) demonstrates that <span class="hlt">electrons</span> can be thermally activated in an intrinsic GaPSb film. Moreover, the observed carrier density dependence on temperature also supports the coexistence of VRH and the activated behavior. It is shown that the carriers are delocalized either with increasing temperature or magnetic field in GaPSb. Our new experimental results provide important information regarding GaPSb which may well lay the foundation for possible GaPSb-based device applications such as in high-<span class="hlt">electron</span>-mobility transistor and heterojunction bipolar transistors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21118673','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21118673"><span>Physiology of PSI cyclic <span class="hlt">electron</span> <span class="hlt">transport</span> in higher plants.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Johnson, Giles N</p> <p>2011-03-01</p> <p>Having long been debated, it is only in the last few years that a concensus has emerged that the cyclic flow of <span class="hlt">electrons</span> around Photosystem I plays an important and general role in the photosynthesis of higher plants. Two major pathways of cyclic flow have been identified, involving either a complex termed NDH or mediated via a pathway involving a protein PGR5 and two functions have been described-to generate ATP and to provide a pH gradient inducing non-photochemical quenching. The best evidence for the occurrence of the two pathways comes from measurements under stress conditions-high light, drought and extreme temperatures. In this review, the possible relative functions and importance of the two pathways is discussed as well as evidence as to how the flow through these pathways is regulated. Our growing knowledge of the proteins involved in cyclic <span class="hlt">electron</span> flow will, in the future, enable us to understand better the occurrence and diversity of cyclic <span class="hlt">electron</span> <span class="hlt">transport</span> pathways. This article is part of a Special Issue entitled: Regulation of <span class="hlt">Electron</span> <span class="hlt">Transport</span> in Chloroplasts. Copyright © 2010 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4738282','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4738282"><span>Control of <span class="hlt">electronic</span> <span class="hlt">transport</span> in graphene by electromagnetic dressing</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kristinsson, K.; Kibis, O. V.; Morina, S.; Shelykh, I. A.</p> <p>2016-01-01</p> <p>We demonstrated theoretically that the renormalization of the <span class="hlt">electron</span> energy spectrum near the Dirac point of graphene by a strong high-frequency electromagnetic field (dressing field) drastically depends on polarization of the field. Namely, linear polarization results in an anisotropic gapless energy spectrum, whereas circular polarization leads to an isotropic gapped one. As a consequence, the stationary (dc) <span class="hlt">electronic</span> <span class="hlt">transport</span> in graphene strongly depends on parameters of the dressing field: A circularly polarized field monotonically decreases the isotropic conductivity of graphene, whereas a linearly polarized one results in both giant anisotropy of conductivity (which can reach thousands of percents) and the oscillating behavior of the conductivity as a function of the field intensity. Since the predicted phenomena can be observed in a graphene layer irradiated by a monochromatic electromagnetic wave, the elaborated theory opens a substantially new way to control <span class="hlt">electronic</span> properties of graphene with light. PMID:26838371</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26838371','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26838371"><span>Control of <span class="hlt">electronic</span> <span class="hlt">transport</span> in graphene by electromagnetic dressing.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kristinsson, K; Kibis, O V; Morina, S; Shelykh, I A</p> <p>2016-02-03</p> <p>We demonstrated theoretically that the renormalization of the <span class="hlt">electron</span> energy spectrum near the Dirac point of graphene by a strong high-frequency electromagnetic field (dressing field) drastically depends on polarization of the field. Namely, linear polarization results in an anisotropic gapless energy spectrum, whereas circular polarization leads to an isotropic gapped one. As a consequence, the stationary (dc) <span class="hlt">electronic</span> <span class="hlt">transport</span> in graphene strongly depends on parameters of the dressing field: A circularly polarized field monotonically decreases the isotropic conductivity of graphene, whereas a linearly polarized one results in both giant anisotropy of conductivity (which can reach thousands of percents) and the oscillating behavior of the conductivity as a function of the field intensity. Since the predicted phenomena can be observed in a graphene layer irradiated by a monochromatic electromagnetic wave, the elaborated theory opens a substantially new way to control <span class="hlt">electronic</span> properties of graphene with light.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28813368','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28813368"><span><span class="hlt">Electronic</span> <span class="hlt">transport</span> properties of graphene doped by gallium.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mach, J; Procházka, P; Bartošík, M; Nezval, D; Piastek, J; Hulva, J; Švarc, V; Konečný, M; Kormoš, L; Šikola, T</p> <p>2017-10-13</p> <p>In this work we present the effect of low dose gallium (Ga) deposition (<4 ML) performed in UHV (10(-7) Pa) on the <span class="hlt">electronic</span> doping and charge carrier scattering in graphene grown by chemical vapor deposition. In situ graphene <span class="hlt">transport</span> measurements performed with a graphene field-effect transistor structure show that at low Ga coverages a graphene layer tends to be strongly n-doped with an efficiency of 0.64 <span class="hlt">electrons</span> per one Ga atom, while the further deposition and Ga cluster formation results in removing <span class="hlt">electrons</span> from graphene (less n-doping). The experimental results are supported by the density functional theory calculations and explained as a consequence of distinct interaction between graphene and Ga atoms in case of individual atoms, layers, or clusters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Nanot..28O5203M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Nanot..28O5203M"><span><span class="hlt">Electronic</span> <span class="hlt">transport</span> properties of graphene doped by gallium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mach, J.; Procházka, P.; Bartošík, M.; Nezval, D.; Piastek, J.; Hulva, J.; Švarc, V.; Konečný, M.; Kormoš, L.; Šikola, T.</p> <p>2017-10-01</p> <p>In this work we present the effect of low dose gallium (Ga) deposition (<4 ML) performed in UHV (10‑7 Pa) on the <span class="hlt">electronic</span> doping and charge carrier scattering in graphene grown by chemical vapor deposition. In situ graphene <span class="hlt">transport</span> measurements performed with a graphene field-effect transistor structure show that at low Ga coverages a graphene layer tends to be strongly n-doped with an efficiency of 0.64 <span class="hlt">electrons</span> per one Ga atom, while the further deposition and Ga cluster formation results in removing <span class="hlt">electrons</span> from graphene (less n-doping). The experimental results are supported by the density functional theory calculations and explained as a consequence of distinct interaction between graphene and Ga atoms in case of individual atoms, layers, or clusters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010APS..MARJ21009E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010APS..MARJ21009E"><span><span class="hlt">Electron</span> <span class="hlt">transport</span> in graphene at extremely high carrier doping</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Efetov, Dmitri; Kim, Philip</p> <p>2010-03-01</p> <p>Owing to the low dimensionality, carrier doping in graphene can be significantly changed by the electric field effect or the chemical adsorption of gaseous dopands. At extremely high doping levels, where carrier densities reach beyond 10^14 cm-2 the <span class="hlt">electronic</span> structure at the Fermi level of graphene is expected to be substantially modified, as higher band structure effects such as trigonal warping or Fermi surface renormalization due to <span class="hlt">electron</span>-phonon coupling take place. In this presentation we will present <span class="hlt">electron</span> <span class="hlt">transport</span> of highly doped graphene samples. By employing a poly(ethylene oxide)-LiClO4 electrolyte gate we achieve unpreceded carrier densities up to 4x10^14 cm-2 in graphene single and bilayers, attaining a Fermi energy change of ˜ 2 eV away from the charge neutrality point. We will present resistivity, as well as Magneto-resistance and Hall measurements in this extreme carrier doping limit.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1086379','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1086379"><span>Effect of Salts and <span class="hlt">Electron</span> <span class="hlt">Transport</span> on the Conformation of Isolated Chloroplasts. II. <span class="hlt">Electron</span> Microscopy 1</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Izawa, Seikichi; Good, Norman E.</p> <p>1966-01-01</p> <p>Spinach chloroplasts isolated in media containing salts and the rare chloroplasts which are still within their envelopes alike retain grana similar to those seen in chloroplasts in situ. Chloroplasts isolated in low-salt media lose their grana without losing any chlorophyll. These grana-free chloroplasts are considerably swollen and consist almost entirely of continuous sheets of paired-membrane structures. These double structures, the lamellae, are only loosely held together, primarily at the edges, by tenuous material which does not react with permanganate. Addition of salts (methylamine hydrochloride, NaCl, MgCl2) to the grana-free low-salt chloroplasts provide strong interlamellar attractions. These attractions result in a stacking of the lamellae which is sometimes almost random but sometimes results in regular structures indistinguishable from the original grana. The phosphorylation-uncoupler atebrin causes further swelling of the chloroplasts in the absence of <span class="hlt">electron</span> <span class="hlt">transport</span> by increasing the space between the paired membranes of the lamellae. The rapid <span class="hlt">electron</span> <span class="hlt">transport</span> (Hill reaction) made possible by atebrin-uncoupling is associated with a great decrease in chloroplast volume. This decrease results from a collapsing together of the widely separated lamellar membrane pairs. The pairs approach each other so closely that they usually appear as a single membrane when viewed with the <span class="hlt">electron</span> microscope. The much slower <span class="hlt">electron</span> <span class="hlt">transport</span> which occurs in the absence of uncouplers is associated with a similar but smaller decrease in the space between the lamellar membrane pairs. Chloroplasts swell during the rapid <span class="hlt">electron</span> <span class="hlt">transport</span> made possible by the phosphorylation-uncoupler methylamine. This swelling is accompanied by a degree of membrane distortion which precludes an interpretation of the mechanism. As with atebrin-faciliated <span class="hlt">electron</span> <span class="hlt">transport</span>, obviously paired membranes disappear but it is not yet clear whether this is by association or</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20030016689','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20030016689"><span><span class="hlt">Electronic</span> Components and Circuits for Extreme Temperature <span class="hlt">Environments</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Patterson, Richard L.; Hammoud, Ahmad; Dickman, John E.; Gerber, Scott</p> <p>2003-01-01</p> <p>Planetary exploration missions and deep space probes require electrical power management and control systems that are capable of efficient and reliable operation in very low temperature <span class="hlt">environments</span>. Presently, spacecraft operating in the cold <span class="hlt">environment</span> of deep space carry a large number of radioisotope heating units in order to maintain the surrounding temperature of the on-board <span class="hlt">electronics</span> at approximately 20 C. <span class="hlt">Electronics</span> capable of operation at cryogenic temperatures will not only tolerate the hostile <span class="hlt">environment</span> of deep space but also reduce system size and weight by eliminating or reducing the radioisotope heating units and their associate structures; thereby reducing system development as well as launch costs. In addition, power <span class="hlt">electronic</span> circuits designed for operation at low temperatures are expected to result in more efficient systems than those at room temperature. This improvement results from better behavior and tolerance in the electrical and thermal properties of semiconductor and dielectric materials at low temperatures. The Low Temperature <span class="hlt">Electronics</span> Program at the NASA Glenn Research Center focuses on research and development of electrical components, circuits, and systems suitable for applications in the aerospace <span class="hlt">environment</span> and deep space exploration missions. Research is being conducted on devices and systems for reliable use down to cryogenic temperatures. Some of the commercial-off-the-shelf as well as developed components that are being characterized include switching devices, resistors, magnetics, and capacitors. Semiconductor devices and integrated circuits including digital-to-analog and analog-to-digital converters, DC/DC converters, operational amplifiers, and oscillators are also being investigated for potential use in low temperature applications. An overview of the NASA Glenn Research Center Low Temperature <span class="hlt">Electronic</span> Program will be presented in this paper. A description of the low temperature test facilities along with</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005APS..MARW35003R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005APS..MARW35003R"><span>Tools for Studying <span class="hlt">Electron</span> and Spin <span class="hlt">Transport</span> in Single Molecules</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ralph, Daniel C.</p> <p>2005-03-01</p> <p>Experiments in the field of single-molecule <span class="hlt">electronics</span> are challenging in part because it can be very difficult to control and characterize the device structure. Molecules contacted by metal electrodes cannot easily be imaged by microscopy techniques. Moreover, if one attempts to characterize the device structure simply by measuring a current-voltage curve, it is easy to mistake nonlinear <span class="hlt">transport</span> across a bare tunnel junction or a metallic short for a molecular signal. I will discuss the development of a set of experimental test structures that enable the properties of a molecular device to be tuned controllably in-situ, so that the <span class="hlt">transport</span> mechanisms can be studied more systematically and compared with theoretical predictions. My collaborators and I are developing the means to use several different types of such experimental "knobs" in coordination: electrostatic gating to shift the energy levels in a molecule, mechanical motion to adjust the molecular configuration or the molecule-electrode coupling strength, illumination with light to promote <span class="hlt">electrons</span> to excited states or to make and break chemical bonds, and the use of ferromagnetic electrodes to study spin-polarized <span class="hlt">transport</span>. Our work so far has provided new insights into Kondo physics, the coupling between a molecule's <span class="hlt">electronic</span> and mechanical degrees of freedom, and spin <span class="hlt">transport</span> through a molecule between magnetic electrodes. Collaborators: Radek Bialczak, Alex Champagne, Luke Donev, Jonas Goldsmith, Jacob Grose, Janice Guikema, Jiwoong Park, Josh Parks, Abhay Pasupathy, Jason Petta, Sara Slater, Burak Ulgut, Alexander Soldatov, H'ector Abruña, and Paul McEuen.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhRvB..91l5419M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhRvB..91l5419M"><span><span class="hlt">Electron</span>-vibron coupling effects on <span class="hlt">electron</span> <span class="hlt">transport</span> via a single-molecule magnet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McCaskey, Alexander; Yamamoto, Yoh; Warnock, Michael; Burzurí, Enrique; van der Zant, Herre S. J.; Park, Kyungwha</p> <p>2015-03-01</p> <p>We investigate how the <span class="hlt">electron</span>-vibron coupling influences <span class="hlt">electron</span> <span class="hlt">transport</span> via an anisotropic magnetic molecule, such as a single-molecule magnet (SMM) Fe4, by using a model Hamiltonian with parameter values obtained from density-functional theory (DFT). The magnetic anisotropy parameters, vibrational energies, and <span class="hlt">electron</span>-vibron coupling strengths of the Fe4 are computed using DFT. A giant spin model is applied to the Fe4 with only two charge states, specifically a neutral state with a total spin S =5 and a singly charged state with S =9 /2 , which is consistent with our DFT result and experiments on Fe4 single-molecule transistors. In sequential <span class="hlt">electron</span> tunneling, we find that the magnetic anisotropy gives rise to new features in the conductance peaks arising from vibrational excitations. In particular, the peak height shows a strong, unusual dependence on the direction as well as magnitude of applied B field. The magnetic anisotropy also introduces vibrational satellite peaks whose position and height are modified with the direction and magnitude of applied B field. Furthermore, when multiple vibrational modes with considerable <span class="hlt">electron</span>-vibron coupling have energies close to one another, a low-bias current is suppressed, independently of gate voltage and applied B field, although that is not the case for a single mode with a similar <span class="hlt">electron</span>-vibron coupling. In the former case, the conductance peaks reveal a stronger B -field dependence than in the latter case. The new features appear because the magnetic anisotropy barrier is of the same order of magnitude as the energies of vibrational modes with significant <span class="hlt">electron</span>-vibron coupling. Our findings clearly show the interesting interplay between magnetic anisotropy and <span class="hlt">electron</span>-vibron coupling in <span class="hlt">electron</span> <span class="hlt">transport</span> via the Fe4. Similar behavior can be observed in <span class="hlt">transport</span> via other anisotropic magnetic molecules.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=217209','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=217209"><span>Aerotaxis in Salmonella typhimurium: role of <span class="hlt">electron</span> <span class="hlt">transport</span>.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Laszlo, D J; Taylor, B L</p> <p>1981-01-01</p> <p>Sensory transduction in aerotaxis required <span class="hlt">electron</span> <span class="hlt">transport</span>, in contrast to chemotaxis, which is independent of <span class="hlt">electron</span> <span class="hlt">transport</span>. Assays for aerotaxis were developed by employing spatial and temporal oxygen gradients imposed independently of respiration. By varying the step increase in oxygen concentration in the temporal assay, the dose-response relationship was obtained for aerotaxis in Salmonella typhimurium. A half-maximal response at 0.4 microM oxygen and inhibition by 5 mM KCN suggested that the "receptor" for aerotaxis is cytochrome o. The response was independent of adenosine triphosphate formation via oxidative phosphorylation but did correlate with changes in membrane potential monitored with the fluorescent cyanine dye diS-C3-(5). Nitrate and fumarate, which are alternative <span class="hlt">electron</span> acceptors for the respiratory chain in S. typhimurium, inhibited aerotaxis when nitrate reductase and fumarate reductase were induced. These results support the hypothesis that taxis to oxygen, nitrate, and fumarate is mediated by the <span class="hlt">electron</span> <span class="hlt">transport</span> system and by changes in the proton motive force. Aerotaxis was normal in Escherichia coli mutants that were defective in the tsr, tar, or trg genes; in S. typhimurium, oxygen did not stimulate methylation of the products of these genes. A cheC mutant which shows an inverse response to chemoattractants also gave an inverse response to oxygen. Therefore, aerotaxis is transduced by a distinct and unidentified signally protein but is focused into the common chemosensory pathway before the step involving the cheC product. When S. typhimurium became anaerobic, the decreased proton motive force from glycolysis supported slow swimming but not tumbling, indicating that a minimum proton motive force was required for tumbling. The bacteria rapidly adapted to the anaerobic condition and resumed tumbling after about 3 min. The adaptation period was much shorter when the bacteria had been previously grown anaerobically. Images PMID</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20703910','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20703910"><span>Meeting the ONCHIT population health mandate: a proposed model for security in selective <span class="hlt">transportable</span> distributed <span class="hlt">environments</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lorence, Daniel; Chin, John; Richards, Michael</p> <p>2010-08-01</p> <p>Goal Two of the US ONCHIT Plan focuses on enabling the use of <span class="hlt">electronic</span> health information for critical health improvement activities that promote the health of targeted communities, and the US population as a whole. Because of the focus on communities and populations, the activities under this second goal differ fundamentally from those of the first goal, which focus on the care of individuals. Proposed here is a model for health information management in such population-based <span class="hlt">environments</span>, which allows selective access and use of information, and maintains <span class="hlt">transportability</span> while ensuring security and confidentiality.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080032798','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080032798"><span>Technology Developments in Radiation-Hardened <span class="hlt">Electronics</span> for Space <span class="hlt">Environments</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Keys, Andrew S.; Howell, Joe T.</p> <p>2008-01-01</p> <p>The Radiation Hardened <span class="hlt">Electronics</span> for Space <span class="hlt">Environments</span> (RHESE) project consists of a series of tasks designed to develop and mature a broad spectrum of radiation hardened and low temperature <span class="hlt">electronics</span> technologies. Three approaches are being taken to address radiation hardening: improved material hardness, design techniques to improve radiation tolerance, and software methods to improve radiation tolerance. Within these approaches various technology products are being addressed including Field Programmable Gate Arrays (FPGA), Field Programmable Analog Arrays (FPAA), MEMS, Serial Processors, Reconfigurable Processors, and Parallel Processors. In addition to radiation hardening, low temperature extremes are addressed with a focus on material and design approaches. System level applications for the RHESE technology products are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/accomplishments/documents/fullText/ACC0141.pdf','DOE-RDACC'); return false;" href="http://www.osti.gov/accomplishments/documents/fullText/ACC0141.pdf"><span>Helium, Iron and <span class="hlt">Electron</span> Particle <span class="hlt">Transport</span> and Energy <span class="hlt">Transport</span> Studies on the TFTR Tokamak</span></a></p> <p><a target="_blank" href="http://www.osti.gov/accomplishments/fieldedsearch.html">DOE R&D Accomplishments Database</a></p> <p>Synakowski, E. J.; Efthimion, P. C.; Rewoldt, G.; Stratton, B. C.; Tang, W. M.; Grek, B.; Hill, K. W.; Hulse, R. A.; Johnson, D .W.; Mansfield, D. K.; McCune, D.; Mikkelsen, D. R.; Park, H. K.; Ramsey, A. T.; Redi, M. H.; Scott, S. D.; Taylor, G.; Timberlake, J.; Zarnstorff, M. C. (Princeton Univ., NJ (United States). Plasma Physics Lab.); Kissick, M. W. (Wisconsin Univ., Madison, WI (United States))</p> <p>1993-03-01</p> <p>Results from helium, iron, and <span class="hlt">electron</span> <span class="hlt">transport</span> on TFTR in L-mode and Supershot deuterium plasmas with the same toroidal field, plasma current, and neutral beam heating power are presented. They are compared to results from thermal <span class="hlt">transport</span> analysis based on power balance. Particle diffusivities and thermal conductivities are radially hollow and larger than neoclassical values, except possibly near the magnetic axis. The ion channel dominates over the <span class="hlt">electron</span> channel in both particle and thermal diffusion. A peaked helium profile, supported by inward convection that is stronger than predicted by neoclassical theory, is measured in the Supershot The helium profile shape is consistent with predictions from quasilinear electrostatic drift-wave theory. While the perturbative particle diffusion coefficients of all three species are similar in the Supershot, differences are found in the L-Mode. Quasilinear theory calculations of the ratios of impurity diffusivities are in good accord with measurements. Theory estimates indicate that the ion heat flux should be larger than the <span class="hlt">electron</span> heat flux, consistent with power balance analysis. However, theoretical values of the ratio of the ion to <span class="hlt">electron</span> heat flux can be more than a factor of three larger than experimental values. A correlation between helium diffusion and ion thermal <span class="hlt">transport</span> is observed and has favorable implications for sustained ignition of a tokamak fusion reactor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28915753','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28915753"><span>Non-renewal statistics for <span class="hlt">electron</span> <span class="hlt">transport</span> in a molecular junction with <span class="hlt">electron</span>-vibration interaction.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kosov, Daniel S</p> <p>2017-09-14</p> <p>Quantum <span class="hlt">transport</span> of <span class="hlt">electrons</span> through a molecule is a series of individual <span class="hlt">electron</span> tunneling events separated by stochastic waiting time intervals. We study the emergence of temporal correlations between successive waiting times for the <span class="hlt">electron</span> <span class="hlt">transport</span> in a vibrating molecular junction. Using the master equation approach, we compute the joint probability distribution for waiting times of two successive tunneling events. We show that the probability distribution is completely reset after each tunneling event if molecular vibrations are thermally equilibrated. If we treat vibrational dynamics exactly without imposing the equilibration constraint, the statistics of <span class="hlt">electron</span> tunneling events become non-renewal. Non-renewal statistics between two waiting times τ1 and τ2 means that the density matrix of the molecule is not fully renewed after time τ1 and the probability of observing waiting time τ2 for the second <span class="hlt">electron</span> transfer depends on the previous <span class="hlt">electron</span> waiting time τ1. The strong <span class="hlt">electron</span>-vibration coupling is required for the emergence of the non-renewal statistics. We show that in the Franck-Condon blockade regime, extremely rare tunneling events become positively correlated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011InPhT..54..204T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011InPhT..54..204T"><span>Modelling of <span class="hlt">electronic</span> <span class="hlt">transport</span> in Quantum Well Infrared Photodetectors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Trinité, Virginie; Ouerghemmi, Ezzeddine; Guériaux, Vincent; Carras, Mathieu; Nedelcu, Alexandru; Costard, Eric; Nagle, Julien</p> <p>2011-05-01</p> <p>Our interest is to model the <span class="hlt">electronic</span> <span class="hlt">transport</span> in Quantum Well Infrared Photodetectors (QWIPs). Standard modelling was based on self-consistent calculation of the non-uniform electric field with empirical description of the <span class="hlt">electron</span> capture (Thibaudeau et al., 1996 [17]). Realistic empirical parameters had to be extracted from experiment, consequently purely numerical studies were not possible. Moreover, this approach allowed only a qualitative description of <span class="hlt">transport</span> phenomena. In order to get rid of adjustable parameters, we have changed for a modelling based on the microscopic description of the <span class="hlt">transport</span> (Jovanović et al., 2004 [11]). We have applied this modelling to the design of a variety of QWIPs. For example, excellent agreement with experimental dark current-voltage curves for different sizes of the barriers is demonstrated on a 8 μm detector over more than 6 orders of magnitude. The behaviour with respect to temperature on a wide range (30-200 K) is also well reproduced on this device as well as on a 17 μm detector. Those promising results confirm that this approach can give not only a good quantitative agreement but can also be a useful predictive tool.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhRvB..90t5416W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhRvB..90t5416W"><span><span class="hlt">Electron</span> <span class="hlt">transport</span> in multiterminal networks of Majorana bound states</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weithofer, Luzie; Recher, Patrik; Schmidt, Thomas L.</p> <p>2014-11-01</p> <p>We investigate <span class="hlt">electron</span> <span class="hlt">transport</span> through multiterminal networks hosting Majorana bound states (MBS) in the framework of full counting statistics. In particular, we apply our general results to T-shaped junctions of two Majorana nanowires. When the wires are in the topologically nontrivial regime, three MBS are localized near the outer ends of the wires, while one MBS is localized near the crossing point, and when the lengths of the wires are finite adjacent MBS can overlap. We propose a combination of current and cross-correlation measurements to reveal the predicted coupling of four Majoranas in a topological T junction. Interestingly, we show that the elementary <span class="hlt">transport</span> processes at the central lead are different compared to the outer leads, giving rise to characteristic nonlocal signatures in <span class="hlt">electronic</span> <span class="hlt">transport</span>. We find quantitative agreement between our analytical model and numerical simulations of a tight-binding model. Using the numerical simulations, we discuss the effect of weak disorder on the current and the cross-correlation functions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhDT.......236M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhDT.......236M"><span><span class="hlt">Electronic</span> Structure and <span class="hlt">Transport</span> in Solids from First Principles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mustafa, Jamal Ibrahim</p> <p></p> <p>The focus of this dissertation is the determination of the <span class="hlt">electronic</span> structure and trans- port properties of solids. We first review some of the theory and computational methodology used in the calculation of <span class="hlt">electronic</span> structure and materials properties. Throughout the dissertation, we make extensive use of state-of-the-art software packages that implement density functional theory, density functional perturbation theory, and the GW approximation, in addition to specialized methods for interpolating matrix elements for extremely accurate results. The first application of the computational framework introduced is the determination of band offsets in semiconductor heterojunctions using a theory of quantum dipoles at the interface. This method is applied to the case of heterojunction formed between a new metastable phase of silicon, with a rhombohedral structure, and cubic silicon. Next, we introduce a novel method for the construction of localized Wannier functions, which we have named the optimized projection functions method (OPFM). We illustrate the method on a variety of systems and find that it can reliably construct localized Wannier functions with minimal user intervention. We further develop the OPFM to investigate a class of materials called topological insulators, which are insulating in the bulk but have conductive surface states. These properties are a result of a nontrivial topology in their band structure, which has interesting effects on the character of the Wannier functions. In the last sections of the main text, the noble metals are studied in great detail, including their <span class="hlt">electronic</span> properties and carrier dynamics. In particular, we investigate, the Fermi surface properties of the noble metals, specifically <span class="hlt">electron</span>-phonon scattering lifetimes, and subsequently the <span class="hlt">transport</span> properties determined by carriers on the Fermi surface. To achieve this, a novel sampling technique is developed, with wide applicability to <span class="hlt">transport</span> calculations</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010APS..MARZ14001C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010APS..MARZ14001C"><span><span class="hlt">Electronic</span> and <span class="hlt">transport</span> properties of heme-b adsorbed on graphene nanoribbons</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cruz-Silva, Eduardo; Bojorquez-Avitia, Marcia; Cruz-Silva, Rodolfo; Lopez-Urias, Florentino; Meunier, Vincent; Terrones, Mauricio; Sumpter, Bobby G.</p> <p>2010-03-01</p> <p>Heme-B is the prosthetic group of several hemoproteins, such as several peroxidases and hemoglobin. It contains an Iron atom that can be oxidized or reduced depending on its <span class="hlt">environment</span>. Changes in Iron oxidation state enable diverse biological functions like oxygen <span class="hlt">transport</span> and <span class="hlt">electron</span> transfer. In this work, we present a quantum density functional study on the adsorption of a heme-b group in graphene. The effects of heme-b adsorption on the graphene <span class="hlt">electronic</span> structure will be shown. These changes have clear effects on the quantum <span class="hlt">transport</span> properties of graphene, which coupled with the affinity of heme-b group to molecules like oxygen, carbon dioxide and carbon monoxide, could help to develop new graphene based amperometric biosensors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/950776','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/950776"><span>Momentum <span class="hlt">Transport</span> in <span class="hlt">Electron</span>-Dominated Spherical Torus Plasmas</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kaye, S. M.; Solomon, W.; Bell, R. E.; LeBlanc, B. P.; Levinton, F.; Menard, J.; Rewoldt, G.; Sabbagh, S.; Wang, W.; Yuh, H.</p> <p>2009-02-24</p> <p>The National Spherical Torus Experiment (NSTX) operates between 0.35 and 0.55 T, which, when coupled to up to 7 MW of neutral beam injection, leads to central rotation velocities in excess of 300 km/s and ExB shearing rates up to 1 MHz. This level of ExB shear can be up to a factor of five greater than typical linear growth rates of long-wavelength ion (e.g., ITG) modes, at least partially suppressing these instabilities. Evidence for this turbulence suppression is that the inferred diffusive ion thermal flux in NSTX H-modes is often at the neoclassical level, and thus these plasmas operate in an <span class="hlt">electron</span>-dominated <span class="hlt">transport</span> regime. Analysis of experiments using n=3 magnetic fields to change plasma rotation indicate that local rotation shear influences local <span class="hlt">transport</span> coefficients, most notably the ion thermal diffusivity, in a manner consistent with suppression of the low-k turbulence by this rotation shear. The value of the effective momentum diffusivity, as inferred from steady-state momentum balance, is found to be larger than the neoclassical value. Results of perturbative experiments indicate inward pinch velocities up to 40 m/s and perturbative momentum diffusivities of up to 4 m2/s, which are larger by a factor of several than those values inferred from steady-state analysis. The inferred pinch velocity values are consistent with values based on theories in which low-k turbulence drives the inward momentum pinch. Thus, in Spherical Tori (STs), while the neoclassical ion energy <span class="hlt">transport</span> effects can be relatively high and dominate the ion energy <span class="hlt">transport</span>, the neoclassical momentum <span class="hlt">transport</span> effects are near zero, meaning that <span class="hlt">transport</span> of momentum is dominated by any low-k turbulence that exists.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhCS.774a2103P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhCS.774a2103P"><span><span class="hlt">Transport</span> properties of copper with excited <span class="hlt">electron</span> subsystem</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Petrov, Yu V.; Migdal, K. P.; Knyazev, D. V.; Inogamov, N. A.; Levashov, P. R.</p> <p>2016-11-01</p> <p>We have investigated <span class="hlt">transport</span> properties of an <span class="hlt">electron</span> subsystem of copper heated by a femtosecond laser pulse. These properties change greatly in comparison with the room temperature solid metal. The <span class="hlt">electron</span> temperature and pressure profiles significantly depend on these properties in bulk laser targets according to the two-temperature (2T) model. These profiles at the 2T stage are responsible for shock and rarefaction waves' formation. We have developed the analytical model of electroconductivity and heat conductivity of copper which takes into account changes of density, <span class="hlt">electron</span> and ion temperatures. The model is based on the solution of the Boltzmann equation in the relaxation time approximation for consideration of <span class="hlt">electron</span> collisions. Also we have carried out the first-principles calculations using the Kubo-Greenwood theory, methods of pseudopotential and linear augmented plane waves which are necessary to evaluate <span class="hlt">electron</span> wavefunctions. We have provided the check of convergence of all parameters of our first-principles calculations. The results of our analytical model for electro- and heat conductivities are in good agreement with the data obtained using the linearized augmented plane wave (LAPW) method.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22412974','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22412974"><span><span class="hlt">Electron</span> and hole <span class="hlt">transport</span> in ambipolar, thin film pentacene transistors</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Saudari, Sangameshwar R.; Kagan, Cherie R.</p> <p>2015-01-21</p> <p>Solution-processed, ambipolar, thin-film pentacene field-effect transistors were employed to study both <span class="hlt">electron</span> and hole <span class="hlt">transport</span> simultaneously in a single, organic solid-state device. <span class="hlt">Electron</span> and hole mobilities were extracted from the respective unipolar saturation regimes and show thermally activated behavior and gate voltage dependence. We fit the gate voltage dependent saturation mobility to a power law to extract the characteristic Meyer-Neldel (MN) energy, a measure of the width of the exponential distribution of localized states extending into the energy gap of the organic semiconductor. The MN energy is ∼78 and ∼28 meV for <span class="hlt">electrons</span> and holes, respectively, which reflects a greater density of localized tail states for <span class="hlt">electrons</span> than holes. This is consistent with the lower measured <span class="hlt">electron</span> than hole mobility. For holes, the well-behaved linear regime allows for four-point probe measurement of the contact resistance independent mobility and separate characterization of the width of the localized density of states, yielding a consistent MN energy of 28 meV.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017BGeo...14..683B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017BGeo...14..683B"><span>Long-distance <span class="hlt">electron</span> <span class="hlt">transport</span> occurs globally in marine sediments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Burdorf, Laurine D. W.; Tramper, Anton; Seitaj, Dorina; Meire, Lorenz; Hidalgo-Martinez, Silvia; Zetsche, Eva-Maria; Boschker, Henricus T. S.; Meysman, Filip J. R.</p> <p>2017-02-01</p> <p>Recently, long filamentous bacteria have been reported conducting <span class="hlt">electrons</span> over centimetre distances in marine sediments. These so-called cable bacteria perform an electrogenic form of sulfur oxidation, whereby long-distance <span class="hlt">electron</span> <span class="hlt">transport</span> links sulfide oxidation in deeper sediment horizons to oxygen reduction in the upper millimetres of the sediment. Electrogenic sulfur oxidation exerts a strong impact on the local sediment biogeochemistry, but it is currently unknown how prevalent the process is within the seafloor. Here we provide a state-of-the-art assessment of its global distribution by combining new field observations with previous reports from the literature. This synthesis demonstrates that electrogenic sulfur oxidation, and hence microbial long-distance <span class="hlt">electron</span> <span class="hlt">transport</span>, is a widespread phenomenon in the present-day seafloor. The process is found in coastal sediments within different climate zones (off the Netherlands, Greenland, the USA, Australia) and thrives on a range of different coastal habitats (estuaries, salt marshes, mangroves, coastal hypoxic basins, intertidal flats). The combination of a widespread occurrence and a strong local geochemical imprint suggests that electrogenic sulfur oxidation could be an important, and hitherto overlooked, component of the marine cycle of carbon, sulfur and other elements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3374801','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3374801"><span>Artemisinin Inhibits Chloroplast <span class="hlt">Electron</span> <span class="hlt">Transport</span> Activity: Mode of Action</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bharati, Adyasha; Kar, Monaranjan; Sabat, Surendra Chandra</p> <p>2012-01-01</p> <p>Artemisinin, a secondary metabolite produced in Artemisia plant species, besides having antimalarial properties is also phytotoxic. Although, the phytotoxic activity of the compound has been long recognized, no information is available on the mechanism of action of the compound on photosynthetic activity of the plant. In this report, we have evaluated the effect of artemisinin on photoelectron <span class="hlt">transport</span> activity of chloroplast thylakoid membrane. The inhibitory effect of the compound, under in vitro condition, was pronounced in loosely and fully coupled thylakoids; being strong in the former. The extent of inhibition was drastically reduced in the presence of uncouplers like ammonium chloride or gramicidin; a characteristic feature described for energy transfer inhibitors. The compound, on the other hand, when applied to plants (in vivo), behaved as a potent inhibitor of photosynthetic <span class="hlt">electron</span> <span class="hlt">transport</span>. The major site of its action was identified to be the QB; the secondary quinone moiety of photosystemII complex. Analysis of photoreduction kinetics of para-benzoquinone and duroquinone suggest that the inhibition leads to formation of low pool of plastoquinol, which becomes limiting for <span class="hlt">electron</span> flow through photosystemI. Further it was ascertained that the in vivo inhibitory effect appeared as a consequence of the formation of an unidentified artemisinin-metabolite rather than by the interaction of the compound per se. The putative metabolite of artemisinin is highly reactive in instituting the inhibition of photosynthetic <span class="hlt">electron</span> flow eventually reducing the plant growth. PMID:22719995</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009SSEle..53.1009S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009SSEle..53.1009S"><span><span class="hlt">Transport</span> properties in semiconductor-gas discharge <span class="hlt">electronic</span> devices</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sadiq, Y.; (Yücel) Kurt, H.; Albarzanji, A. O.; Alekperov, S. D.; Salamov, B. G.</p> <p>2009-09-01</p> <p>Nonlinear electrical <span class="hlt">transport</span> of semi-insulating (SI) GaAs detector in semiconductor-gas discharge IR image converter (SGDIC) are studied experimentally for a wide range of the gas pressures ( p = 28-55 Torr), interelectrode distances ( d = 445-525 μm) and inner electrode diameters ( D = 12-22 mm) of photocathode. The destabilization of homogeneous state observed in a planar dc-driven structure is due to nonlinear <span class="hlt">transport</span> properties of GaAs photocathode. Experimental investigation of electrical instability in SGDIC structure was analyzed using hysteresis, N-shaped negative differential conductivity (NDC) current voltage characteristics (CVC) and dynamic behavior of current in a wide range of feeding voltage ( U = 590-1000 V) under different IR light intensities incident on cathode material. It is established that hysteresis are related to <span class="hlt">electron</span> capture and emission from EL2 deep center on the detector substrate. We have experimentally investigated domain velocity and <span class="hlt">electron</span> mobility based on well-understood transferred <span class="hlt">electron</span> effect (TEE) for abovementioned nonlinear electrical characteristics of SI GaAs. The experimental findings are in good agreement with estimated results reported by other independent authors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070032045','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070032045"><span>High-Performance, Radiation-Hardened <span class="hlt">Electronics</span> for Space <span class="hlt">Environments</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Keys, Andrew S.; Watson, Michael D.; Frazier, Donald O.; Adams, James H.; Johnson, Michael A.; Kolawa, Elizabeth A.</p> <p>2007-01-01</p> <p>The Radiation Hardened <span class="hlt">Electronics</span> for Space <span class="hlt">Environments</span> (RHESE) project endeavors to advance the current state-of-the-art in high-performance, radiation-hardened <span class="hlt">electronics</span> and processors, ensuring successful performance of space systems required to operate within extreme radiation and temperature <span class="hlt">environments</span>. Because RHESE is a project within the Exploration Technology Development Program (ETDP), RHESE's primary customers will be the human and robotic missions being developed by NASA's Exploration Systems Mission Directorate (ESMD) in partial fulfillment of the Vision for Space Exploration. Benefits are also anticipated for NASA's science missions to planetary and deep-space destinations. As a technology development effort, RHESE provides a broad-scoped, full spectrum of approaches to environmentally harden space <span class="hlt">electronics</span>, including new materials, advanced design processes, reconfigurable hardware techniques, and software modeling of the radiation <span class="hlt">environment</span>. The RHESE sub-project tasks are: SelfReconfigurable <span class="hlt">Electronics</span> for Extreme <span class="hlt">Environments</span>, Radiation Effects Predictive Modeling, Radiation Hardened Memory, Single Event Effects (SEE) Immune Reconfigurable Field Programmable Gate Array (FPGA) (SIRF), Radiation Hardening by Software, Radiation Hardened High Performance Processors (HPP), Reconfigurable Computing, Low Temperature Tolerant MEMS by Design, and Silicon-Germanium (SiGe) Integrated <span class="hlt">Electronics</span> for Extreme <span class="hlt">Environments</span>. These nine sub-project tasks are managed by technical leads as located across five different NASA field centers, including Ames Research Center, Goddard Space Flight Center, the Jet Propulsion Laboratory, Langley Research Center, and Marshall Space Flight Center. The overall RHESE integrated project management responsibility resides with NASA's Marshall Space Flight Center (MSFC). Initial technology development emphasis within RHESE focuses on the hardening of Field Programmable Gate Arrays (FPGA)s and Field Programmable Analog</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999APS..DPP.FP152K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999APS..DPP.FP152K"><span>Experiments on Viscous <span class="hlt">Transport</span> in Pure-<span class="hlt">Electron</span> Plasmas.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kriesel, J. M.; Driscoll, C. F.</p> <p>1999-11-01</p> <p>Viscous <span class="hlt">transport</span> in pure-<span class="hlt">electron</span> plasmas is a rearrangement of particles due to like-particle interactions, leading to the confined global thermal equilibrium state. The measured <span class="hlt">transport</span> is observed to be proportional to the shear in the total (E × B + diamagnetic) fluid rotation of the plasma for both hollow and monotonic rotation profiles. We determine the local viscosity coefficient η in the plasma from measurements of the local flux of particles. The measured viscosity is 50-10^4 times larger than expected from classical <span class="hlt">transport</span> due to short-range velocity-scattering collisions, but is within a factor of 10 agreement with recent theories by O'Neil and Dubin of <span class="hlt">transport</span> due to long-range drift collisions. The measured viscosity scales with magnetic field B and length L roughly as η ∝ B/L. This scaling suggests a finite length enhancement of the viscosity, which occurs because particles interact many times as they bounce axially before they are sheared apart azimuthally.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000PhPl....7.2810B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000PhPl....7.2810B"><span>Linear delta-f simulations of nonlocal <span class="hlt">electron</span> heat <span class="hlt">transport</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brunner, S.; Valeo, E.; Krommes, J. A.</p> <p>2000-07-01</p> <p>Nonlocal <span class="hlt">electron</span> heat <span class="hlt">transport</span> calculations are carried out by making use of some of the techniques developed previously for extending the δf method to <span class="hlt">transport</span> time scale simulations [S. Brunner, E. Valeo, and J. Krommes, Phys. Plasmas 6, 4504 (1999)]. By considering the relaxation of small amplitude temperature perturbations of an homogeneous Maxwellian background, only the linearized Fokker-Planck equation has to be solved, and direct comparisons can be made with the equivalent, nonlocal hydrodynamic approach [V. Yu. Bychenkov et al., Phys. Rev. Lett. 75, 4405 (1995)]. A quasineutrality-conserving algorithm is derived for computing the self-consistent electric fields driving the return currents. In the low-collisionality regime, results illustrate the importance of taking account of nonlocality in both space and time.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5197113','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5197113"><span>Conservative differencing of the <span class="hlt">electron</span> Fokker-Planck <span class="hlt">transport</span> equation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Langdon, A.B.</p> <p>1981-01-12</p> <p>We need to extend the applicability and improve the accuracy of kinetic <span class="hlt">electron</span> <span class="hlt">transport</span> codes. In this paper, special attention is given to modelling of e-e collisions, including the dominant contributions arising from anisotropy. The electric field and spatial gradient terms are also considered. I construct finite-difference analogues to the Fokker-Planck integral-differential collision operator, which conserve the particle number, momentum and energy integrals (sums) regardless of the coarseness of the velocity zoning. Such properties are usually desirable, but are especially useful, for example, when there are spatial regions and/or time intervals in which the plasma is cool, so that the collision operator acts rapidly and the velocity distribution is poorly resolved, yet it is crucial that gross conservation properties be respected in hydro-<span class="hlt">transport</span> applications, such as in the LASNEX code. Some points are raised concerning spatial differencing and time integration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10183507','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10183507"><span>Studies of local <span class="hlt">electron</span> heat <span class="hlt">transport</span> on TFTR</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fredrickson, E.D.; Chang, Z.Y.; Janos, A.; McGuire, K.M.; Scott, S.; Taylor, G.</p> <p>1993-08-16</p> <p>The anomalously fast relaxation of the perturbations to the <span class="hlt">electron</span> temperature profile caused by a sawtooth crash has been studied extensively on TFTR. We will show that on a short timescale the heat pulse is not simply diffusive as has been generally assumed, but that modeling of the heat pulse requires a transient enhancement in {chi}{sub e} following the sawtooth crash. It will be shown that the time-dependent enhancement in {chi}{sub e} predicted by non-linear thermal <span class="hlt">transport</span> models, i.e., incremental {chi} models or the Rebut-Lallia-Watkins <span class="hlt">transport</span> model, is much smaller than that required to explain the anomalies in the heat pulse propagation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1984PhRvB..29.6879H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1984PhRvB..29.6879H"><span>Intersoliton hopping <span class="hlt">transport</span> of <span class="hlt">electrons</span> in molecular crystals</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Howard, I. A.; Conwell, E. M.</p> <p>1984-06-01</p> <p>Quarter-filled-band quasi-one-dimensional compounds which exhibit large Coulomb repulsion between two <span class="hlt">electrons</span> on the same site ("large U") can support the formation of fractionally charged solitons. <span class="hlt">Electron</span> hopping between solitons may contribute substantially to <span class="hlt">transport</span> in these materials. We calculate the intersoliton <span class="hlt">electron</span> hopping rate for transitions mediated by intramolecular phonons and by acoustic phonons. Acoustic phonons are found to be much less effective and are expected to contribute significantly only when intramolecular phonons are not excited or cannot satisfy conservation of energy. For the case of intramolecular phonons, we consider both hopping of an <span class="hlt">electron</span> from a soliton pinned by an impurity to a second soliton which then becomes pinned, and hopping between a pair of solitons, one of which remains free to move. [Owing to the large on-chain dielectric constant (~ 100-1000) in these materials, the solitons are probably not bound except at low temperatures.] The transition rates are used to find the hopping mobility for <span class="hlt">electrons</span> in the soliton levels. Evaluation of the mobility due to the different hopping mechanisms for (N-methylphenazinium)0.54(phenazine)0.46 tetracyanoquinodimethane [(NMP)0.54(Phen)0.46-(TCNQ)] at a temperature of 100 K suggests that, unlike the polyacetylene case, the predominant process at temperatures >~100 K is on-chain hopping, due to the large interchain distances involved. We find a mobility at 100 K of 0.06-1.03 cm2/V sec due to on-chain hopping, mediated by intramolecular phonons, between pinned and free solitons. This mobility should increase at higher temperatures. The thermoelectric power due to the various <span class="hlt">electron</span> hopping processes is calculated as well. We find that for hopping processes involving transitions between pinned and free solitons there is a term in the thermopower involving the soliton pinning energy, in addition to the usual term involving <span class="hlt">electronic</span> energy levels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21439580','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21439580"><span>Numerical Investigation of Laser Propulsion for <span class="hlt">Transport</span> in Water <span class="hlt">Environment</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Han Bing; Li Beibei; Zhang Hongchao; Chen Jun; Shen Zhonghua; Lu Jian; Ni Xiaowu</p> <p>2010-10-08</p> <p>Problems that cumber the development of the laser propulsion in atmosphere and vacuum are discussed. Based on the theory of interaction between high-intensity laser and materials, as air and water, it is proved that <span class="hlt">transport</span> in water <span class="hlt">environment</span> can be impulsed by laser. The process of laser propulsion in water is investigated theoretically and numerically. It shows that not only the laser induced plasma shock wave, but also the laser induced bubble oscillation shock waves and the pressure induced by the collapsing bubble can be used. Many experimental results show that the theory and the numerical results are valid. The numerical result of the contribution of every propulsion source is given in percentage. And the maximum momentum coupling coefficient Cm is given. Laser propulsion in water <span class="hlt">environment</span> can be applied in many fields. For example, it can provide highly controllable forces of the order of micro-Newton ({mu}N) in microsystems, such as the MEMS (Micro-electromechanical Systems). It can be used as minimally invasive surgery tools of high temporal and spatial resolution. It can be used as the propulsion source in marine survey and exploitation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AIPC.1278..165H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AIPC.1278..165H"><span>Numerical Investigation of Laser Propulsion for <span class="hlt">Transport</span> in Water <span class="hlt">Environment</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Han, Bing; Li, Bei-Bei; Zhang, Hong-Chao; Chen, Jun; Shen, Zhong-Hua; Lu, Jian; Ni, Xiao-Wu</p> <p>2010-10-01</p> <p>Problems that cumber the development of the laser propulsion in atmosphere and vacuum are discussed. Based on the theory of interaction between high-intensity laser and materials, as air and water, it is proved that <span class="hlt">transport</span> in water <span class="hlt">environment</span> can be impulsed by laser. The process of laser propulsion in water is investigated theoretically and numerically. It shows that not only the laser induced plasma shock wave, but also the laser induced bubble oscillation shock waves and the pressure induced by the collapsing bubble can be used. Many experimental results show that the theory and the numerical results are valid. The numerical result of the contribution of every propulsion source is given in percentage. And the maximum momentum coupling coefficient Cm is given. Laser propulsion in water <span class="hlt">environment</span> can be applied in many fields. For example, it can provide highly controllable forces of the order of micro-Newton (μN) in microsystems, such as the MEMS (Micro-electromechanical Systems). It can be used as minimally invasive surgery tools of high temporal and spatial resolution. It can be used as the propulsion source in marine survey and exploitation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JChPh.136r4301F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JChPh.136r4301F"><span><span class="hlt">Electron</span> attachment to molecules in a cluster <span class="hlt">environment</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fabrikant, I. I.; Caprasecca, S.; Gallup, G. A.; Gorfinkiel, J. D.</p> <p>2012-05-01</p> <p>Low-energy dissociative <span class="hlt">electron</span> attachment (DEA) to the CF2Cl2 and CF3Cl molecules in a water cluster <span class="hlt">environment</span> is investigated theoretically. Calculations are performed for the water trimer and water hexamer. It is shown that the DEA cross section is strongly enhanced when the attaching molecule is embedded in a water cluster, and that this cross section grows as the number of water molecules in the cluster increases. This growth is explained by a trapping effect that is due to multiple scattering by water molecules while the <span class="hlt">electron</span> is trapped in the cluster <span class="hlt">environment</span>. The trapping increases the resonance lifetime and the negative ion survival probability. This confirms qualitatively existing experiments on <span class="hlt">electron</span> attachment to the CF2Cl2 molecule placed on the surface of H2O ice. The DEA cross sections are shown to be very sensitive to the position of the attaching molecule within the cluster and the orientation of the <span class="hlt">electron</span> beam relative to the cluster.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130013147','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130013147"><span>High Temperature Wireless Communication And <span class="hlt">Electronics</span> For Harsh <span class="hlt">Environment</span> Applications</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hunter, G. W.; Neudeck, P. G.; Beheim, G. M.; Ponchak, G. E.; Chen, L.-Y</p> <p>2007-01-01</p> <p>In order for future aerospace propulsion systems to meet the increasing requirements for decreased maintenance, improved capability, and increased safety, the inclusion of intelligence into the propulsion system design and operation becomes necessary. These propulsion systems will have to incorporate technology that will monitor propulsion component conditions, analyze the incoming data, and modify operating parameters to optimize propulsion system operations. This implies the development of sensors, actuators, and <span class="hlt">electronics</span>, with associated packaging, that will be able to operate under the harsh <span class="hlt">environments</span> present in an engine. However, given the harsh <span class="hlt">environments</span> inherent in propulsion systems, the development of engine-compatible <span class="hlt">electronics</span> and sensors is not straightforward. The ability of a sensor system to operate in a given <span class="hlt">environment</span> often depends as much on the technologies supporting the sensor element as the element itself. If the supporting technology cannot handle the application, then no matter how good the sensor is itself, the sensor system will fail. An example is high temperature <span class="hlt">environments</span> where supporting technologies are often not capable of operation in engine conditions. Further, for every sensor going into an engine <span class="hlt">environment</span>, i.e., for every new piece of hardware that improves the in-situ intelligence of the components, communication wires almost always must follow. The communication wires may be within or between parts, or from the engine to the controller. As more hardware is added, more wires, weight, complexity, and potential for unreliability is also introduced. Thus, wireless communication combined with in-situ processing of data would significantly improve the ability to include sensors into high temperature systems and thus lead toward more intelligent engine systems. NASA Glenn Research Center (GRC) is presently leading the development of <span class="hlt">electronics</span>, communication systems, and sensors capable of prolonged stable</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhDT.........6B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhDT.........6B"><span>Nanoscale <span class="hlt">transport</span> of <span class="hlt">electrons</span> and ions in water</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Boynton, Paul Christopher</p> <p></p> <p>The following dissertation discusses the theoretical study of water on the nanoscale, often involved with essential biological molecules such as DNA and proteins. First I introduce the study of water on the nanoscale and how experimentalists approach confinement with nanopores and nanogaps. Then I discuss the theoretical method we choose for understanding this important biological medium on the molecular level, namely classical molecular dynamics. This leads into <span class="hlt">transport</span> mechanisms that utilize water on the nanoscale, in our case <span class="hlt">electronic</span> and ionic <span class="hlt">transport</span>. On the scale of mere nanometers or less <span class="hlt">electronic</span> <span class="hlt">transport</span> in water enters the tunneling regime, requiring the use of a quantum treatment. In addition, I discuss the importance of water in ionic <span class="hlt">transport</span> and its known effects on biological phenomena such as ion selectivity. Water also has great influence over DNA and proteins, which are both introduced in the context of nanopore sequencing. Several techniques for nanopore sequencing are examined and the importance of protein sequencing is explained. In Chapter 2, we study the effect of volumetric constraints on the structure and <span class="hlt">electronic</span> <span class="hlt">transport</span> properties of distilled water in a nanopore with embedded electrodes. Combining classical molecular dynamics simulations with quantum scattering theory, we show that the structural motifs water assumes inside the pore can be probed directly by tunneling. In Chapter 3, we propose an improvement to the original sequencing by tunneling method, in which N pairs of electrodes are built in series along a synthetic nanochannel. Each current time series for each nucleobase is cross-correlated together, reducing noise in the signals. We show using random sampling of data from classical molecular dynamics, that indeed the sequencing error is significantly reduced as the number of pairs of electrodes, N, increases. In Chapter 4, we propose a new technique for de novo protein sequencing that involves translocating a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA590300','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA590300"><span>Army <span class="hlt">Transportation</span> Systems in a Twenty-First Century Joint Operational <span class="hlt">Environment</span></span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2013-03-01</p> <p>Wheeled Vehicles Classification : Unclassified Five components of the U.S. Army <span class="hlt">Transportation</span> Systems collectively meet...Army <span class="hlt">Transportation</span> Systems in a Twenty-First Century Joint Operational <span class="hlt">Environment</span> by Lieutenant Colonel Mark D. Stimer...<span class="hlt">Transportation</span> Systems in a Twenty-First Century Joint Operational <span class="hlt">Environment</span> 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ChPhL..31e7304W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ChPhL..31e7304W"><span><span class="hlt">Electronic</span> <span class="hlt">Transport</span> of a Molecular Photoswitch with Graphene Nanoribbon Electrodes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Qiu-Hua; Zhao, Peng; Liu, De-Sheng</p> <p>2014-05-01</p> <p>Based on non-equilibrium Green's function formalism and density functional theory calculations, we investigate the <span class="hlt">electronic</span> <span class="hlt">transport</span> properties of 15,16-dinitrile dihydropyrene/cyclophanediene bridged between two zigzag graphene nanoribbon electrodes. Our results demonstrate that the system can exhibit good switching behavior with the maximum on-off ratio high up to 146 which is improved dramatically compared with the case of gold electrodes. Moreover, an obvious negative differential resistance behavior occurs at 0.3 V, making the system have more potential in near future molecular circuits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhLA..381.2107H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhLA..381.2107H"><span><span class="hlt">Electronic</span> <span class="hlt">transport</span> properties in [n]cycloparaphenylenes molecular devices</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, Lizhi; Guo, Yandong; Yan, Xiaohong; Zeng, Hongli; Zhou, Jie</p> <p>2017-07-01</p> <p>The <span class="hlt">electronic</span> <span class="hlt">transport</span> of [n]cycloparaphenylenes ([n]CPPs) is investigated based on nonequilibrium Green's function formalism in combination with the density-functional theory. Negative differential resistance (NDR) phenomenon is observed. Further analysis shows that the reduction of the transmission peak induced by the bias changing near Fermi energy results in the NDR effect. Replacing the electrode (from carbon chain to Au electrode), doping with N atom and changing the size of the nanohoop (n = 5, 6, 8, 10) have also been studied and the NDR still exists, suggesting the NDR behavior is the intrinsic feature of such [n]CPPs systems, which would be quite useful in future nanoelectronic devices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11088933','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11088933"><span><span class="hlt">Electron</span> <span class="hlt">transport</span> in argon in crossed electric and magnetic fields</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ness; Makabe</p> <p>2000-09-01</p> <p>An investigation of <span class="hlt">electron</span> <span class="hlt">transport</span> in argon in the presence of crossed electric and magnetic fields is carried out over a wide range of values of electric and magnetic field strengths. Values of mean energy, ionization rate, drift velocity, and diffusion tensor are reported here. Two unexpected phenomena arise; for certain values of electric and magnetic field we find regions where the swarm mean energy decreases with increasing electric fields for a fixed magnetic field and regions where swarm mean energy increases with increasing magnetic field for a fixed electric field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22555657','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22555657"><span><span class="hlt">Electronic</span> structures and <span class="hlt">transport</span> properties of fluorinated boron nitride nanoribbons.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zeng, Jing; Chen, Ke-Qiu; Sun, Chang Q</p> <p>2012-06-14</p> <p>By applying the nonequilibrium Green's functions and the density-functional theory, we investigate the <span class="hlt">electronic</span> structures and <span class="hlt">transport</span> properties of fluorinated zigzag-edged boron nitride nanoribbons. The results show that the transition between half-metal and semiconductor in zigzag-edged boron nitride nanoribbons can be realized by fluorination at different sites or by the change of the fluorination level. Moreover, the negative differential resistance and varistor-type behaviors can also be observed in such fluorinated zigzag-edged boron nitride nanoribbon devices. Therefore, the fluorination of zigzag-edged boron nitride nanoribbons will provide the possibilities for a multifunctional molecular device design.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22269317','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22269317"><span>Study of <span class="hlt">electronic</span> <span class="hlt">transport</span> properties of doped 8AGNR</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sharma, Uma Shankar; Srivastava, Anurag; Verma, U. P.</p> <p>2014-04-24</p> <p>The <span class="hlt">electronic</span> and <span class="hlt">transport</span> properties of 8-armchair graphene nanoribbon (8AGNR) with defect at different sites are investigated by performing first-principles calculations based on density functional theory (DFT). The calculated results show that the 8AGNR are semiconductor. The introduction of 3d transition metals, creates the nondegenerate states in the conduction band, makes 8AGNR metallic. The computed transmission spectrum confirms that AGNR are semiconducting in nature and their band gap remain unchanged and localized states appear when there is vacancy in their structures, and the conductance decreases due to defects compared with the pristine nanoribbon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21612543','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21612543"><span>Calculation of <span class="hlt">electronic</span> <span class="hlt">transport</span> coefficients of Ag and Au plasma</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Apfelbaum, E. M.</p> <p>2011-12-15</p> <p>The thermoelectric <span class="hlt">transport</span> coefficients of silver and gold plasma have been calculated within the relaxation-time approximation. We considered temperatures of 10-100 kK and densities of {rho} < or approx. 1 g/cm{sup 3}. The plasma composition was calculated using a corresponding system of coupled mass action laws, including the atom ionization up to +4. For momentum cross sections of <span class="hlt">electron</span>-atom scattering we used the most accurate expressions available. The results of our modeling have been compared with other researchers' data whenever possible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JAP...121x4305P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JAP...121x4305P"><span>Coherent manipulation of thermal <span class="hlt">transport</span> by tunable <span class="hlt">electron</span>-photon and <span class="hlt">electron</span>-phonon interaction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Paolucci, Federico; Timossi, Giuliano; Solinas, Paolo; Giazotto, Francesco</p> <p>2017-06-01</p> <p>We propose a system where coherent thermal <span class="hlt">transport</span> between two reservoirs in non-galvanic contact is modulated by independently tuning the <span class="hlt">electron</span>-photon and the <span class="hlt">electron</span>-phonon coupling. The scheme is based on two gate-controlled electrodes capacitively coupled through a dc-SQUID (superconducting quantum interference device) as an intermediate phase-tunable resonator. Thereby the <span class="hlt">electron</span>-photon interaction is modulated by controlling the flux threading the dc-SQUID (superconducting quantum interference device) and the impedance of the two reservoirs, while the <span class="hlt">electron</span>-phonon coupling is tuned by controlling the charge carrier concentration in the electrodes. To quantitatively evaluate the behavior of the system, we propose to exploit the graphene reservoirs. In this case, the scheme can work at temperatures reaching 1 K, with unprecedented temperature modulations as large as 245 mK, transmittance up to 99%, and energy conversion efficiency up to 50%. Finally, the accuracy of heat <span class="hlt">transport</span> control allows us to use this system as an experimental tool to determine the <span class="hlt">electron</span>-phonon coupling in two-dimensional <span class="hlt">electronic</span> systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006APS..MARZ37013T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006APS..MARZ37013T"><span>Theory of <span class="hlt">electron</span>-vibration coupling in the <span class="hlt">electron</span> <span class="hlt">transport</span> of molecular bridges</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tsukada, Masaru; Mitsutake, Kunihiro</p> <p>2006-03-01</p> <p><span class="hlt">Electron</span> <span class="hlt">transport</span> through molecules connecting nano-electrodes is the key issue for molecular devices. The competition and coexistence of the coherent and dissipative <span class="hlt">transport</span> are unresolved issue, in spite of its importance. In this work, this problem is investigated by a novel theoretical approach of an ab initio molecular orbital model with combining polaron effect. When carriers are injected into molecules from electrodes, the structure of the molecule changes, which leads the coupling term of the <span class="hlt">electron</span>/hole and the molecular vibration. The model Hamiltonian for the thiophene oligomer is solved by a variational approach, and a mixed states of dressed polaron with molecular orbital states mediated by the phonon cloud is found. The former and latter are predominant for small or large transfer integral, respectively. The excited states can be calculated in the same framework as the ground state. The overall carrier <span class="hlt">transport</span> properties can be analyzed by solving the master equation with the transition rate estimated by the golden rule including the phonon degrees of freedom. In this theoretical approach, the coherent and dissipative <span class="hlt">electron</span> <span class="hlt">transport</span> through molecular bridges can be described in a uniform systematic way.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JChPh.146i2302K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JChPh.146i2302K"><span>Structure dependent spin selectivity in <span class="hlt">electron</span> <span class="hlt">transport</span> through oligopeptides</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kiran, Vankayala; Cohen, Sidney R.; Naaman, Ron</p> <p>2017-03-01</p> <p>The chiral-induced spin selectivity (CISS) effect entails spin-selective <span class="hlt">electron</span> transmission through chiral molecules. In the present study, the spin filtering ability of chiral, helical oligopeptide monolayers of two different lengths is demonstrated using magnetic conductive probe atomic force microscopy. Spin-specific nanoscale <span class="hlt">electron</span> <span class="hlt">transport</span> studies elucidate that the spin polarization is higher for 14-mer oligopeptides than that of the 10-mer. We also show that the spin filtering ability can be tuned by changing the tip-loading force applied on the molecules. The spin selectivity decreases with increasing applied force, an effect attributed to the increased ratio of radius to pitch of the helix upon compression and increased tilt angles between the molecular axis and the surface normal. The method applied here provides new insights into the parameters controlling the CISS effect.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3896775','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3896775"><span>Orthogonally modulated molecular <span class="hlt">transport</span> junctions for resettable <span class="hlt">electronic</span> logic gates</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Meng, Fanben; Hervault, Yves-Marie; Shao, Qi; Hu, Benhui; Norel, Lucie; Rigaut, Stéphane; Chen, Xiaodong</p> <p>2014-01-01</p> <p>Individual molecules have been demonstrated to exhibit promising applications as functional components in the fabrication of computing nanocircuits. Based on their advantage in chemical tailorability, many molecular devices with advanced <span class="hlt">electronic</span> functions have been developed, which can be further modulated by the introduction of external stimuli. Here, orthogonally modulated molecular <span class="hlt">transport</span> junctions are achieved via chemically fabricated nanogaps functionalized with dithienylethene units bearing organometallic ruthenium fragments. The addressable and stepwise control of molecular isomerization can be repeatedly and reversibly completed with a judicious use of the orthogonal optical and electrochemical stimuli to reach the controllable switching of conductivity between two distinct states. These photo-/electro-cooperative nanodevices can be applied as resettable <span class="hlt">electronic</span> logic gates for Boolean computing, such as a two-input OR and a three-input AND-OR. The proof-of-concept of such logic gates demonstrates the possibility to develop multifunctional molecular devices by rational chemical design. PMID:24394717</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014NatCo...5E3023M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014NatCo...5E3023M"><span>Orthogonally modulated molecular <span class="hlt">transport</span> junctions for resettable <span class="hlt">electronic</span> logic gates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meng, Fanben; Hervault, Yves-Marie; Shao, Qi; Hu, Benhui; Norel, Lucie; Rigaut, Stéphane; Chen, Xiaodong</p> <p>2014-01-01</p> <p>Individual molecules have been demonstrated to exhibit promising applications as functional components in the fabrication of computing nanocircuits. Based on their advantage in chemical tailorability, many molecular devices with advanced <span class="hlt">electronic</span> functions have been developed, which can be further modulated by the introduction of external stimuli. Here, orthogonally modulated molecular <span class="hlt">transport</span> junctions are achieved via chemically fabricated nanogaps functionalized with dithienylethene units bearing organometallic ruthenium fragments. The addressable and stepwise control of molecular isomerization can be repeatedly and reversibly completed with a judicious use of the orthogonal optical and electrochemical stimuli to reach the controllable switching of conductivity between two distinct states. These photo-/electro-cooperative nanodevices can be applied as resettable <span class="hlt">electronic</span> logic gates for Boolean computing, such as a two-input OR and a three-input AND-OR. The proof-of-concept of such logic gates demonstrates the possibility to develop multifunctional molecular devices by rational chemical design.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhyE...82..129F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhyE...82..129F"><span>Reprint of : Time dependent <span class="hlt">electronic</span> <span class="hlt">transport</span> in chiral edge channels</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fève, G.; Berroir, J.-M.; Plaçais, B.</p> <p>2016-08-01</p> <p>We study time dependent <span class="hlt">electronic</span> <span class="hlt">transport</span> along the chiral edge channels of the quantum Hall regime, focusing on the role of Coulomb interaction. In the low frequency regime, the a.c. conductance can be derived from a lumped element description of the circuit. At higher frequencies, the propagation equations of the Coulomb coupled edge channels need to be solved. As a consequence of the interchannel coupling, a charge pulse emitted in a given channel fractionalized in several pulses. In particular, Coulomb interaction between channels leads to the fractionalization of a charge pulse emitted in a given channel in several pulses. We finally study how the Coulomb interaction, and in particular the fractionalization process, affects the propagation of a single <span class="hlt">electron</span> in the circuit. All the above-mentioned topics are illustrated by experimental realizations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhCS.717a2043O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhCS.717a2043O"><span><span class="hlt">Electron</span> <span class="hlt">transport</span> estimated from <span class="hlt">electron</span> spectra using <span class="hlt">electron</span> spectrometer in LFEX laser target experiments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ozaki, T.; Hata, M.; Matsuo, K.; Kojima, S.; Arikawa, Y.; Fujioka, S.; Sakagami, H.; Sunahara, A.; Nagatomo, H.; Johzaki, T.; Yogo, A.; Morace, A.; Zhang, Z.; Shiraga, H.; Sakata, S.; Nagai, T.; Abe, Y.; Lee, S.; Nakai, M.; Nishimura, H.; Azechi, H.; FIREX Group; GXII-LFEX Group</p> <p>2016-05-01</p> <p>Hot <span class="hlt">electrons</span> which are generated from targets irradiated by a high-intense laser are measured by two <span class="hlt">electron</span> spectrometers (ESMs). However, total <span class="hlt">electron</span> energy observed by the ESM is only less than 1%. Hot <span class="hlt">electrons</span> are confined by self-fields due to the huge current. When an external magnetic field of several hundred Tesla is applied during the laser irradiation on targets, the ESM signals always increase. In the simulation, the same result can be obtained. The reason is that the Alfvén limit can be mitigated due to the external longitudinal magnetic field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/763897','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/763897"><span>Interfacial Charge <span class="hlt">Transport</span> in Organic <span class="hlt">Electronic</span> Materials: the Key to a New <span class="hlt">Electronics</span> Technology</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Smith, D.L.; Campbell, I.H.; Davids, P.S.; Heller, C.M.; Laurich, B.K.; Crone, B.K.; Saxena, A.; Bishop, A.R.; Ferraris, J.P.; Yu, Z.G.</p> <p>1999-06-04</p> <p>This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The primary aim of this project is to obtain a basic scientific understanding of electrical <span class="hlt">transport</span> processes at interfaces that contain an organic <span class="hlt">electronic</span> material. Because of their processing advantages and the tunability of their <span class="hlt">electronic</span> properties, organic <span class="hlt">electronic</span> materials are revolutionizing major technological areas such as information display. We completed an investigation of the fundamental <span class="hlt">electronic</span> excitation energies in the prototype conjugated polymer MEH-PPV. We completed a combined theoretical/experimental study of the energy relation between charged excitations in a conjugated polymer and the metal at a polymer/metal interface. We developed a theoretical model that explains injection currents at polymer/metal interfaces. We have made electrical measurements on devices fabricated using the conjugated polymer MEH-PPV a nd a series of metals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/266736','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/266736"><span>Space applications of the MITS <span class="hlt">electron</span>-photon Monte Carlo <span class="hlt">transport</span> code system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kensek, R.P.; Lorence, L.J.; Halbleib, J.A.; Morel, J.E.</p> <p>1996-07-01</p> <p>The MITS multigroup/continuous-energy <span class="hlt">electron</span>-photon Monte Carlo <span class="hlt">transport</span> code system has matured to the point that it is capable of addressing more realistic three-dimensional adjoint applications. It is first employed to efficiently predict point doses as a function of source energy for simple three-dimensional experimental geometries exposed to simulated uniform isotropic planar sources of monoenergetic <span class="hlt">electrons</span> up to 4.0 MeV. Results are in very good agreement with experimental data. It is then used to efficiently simulate dose to a detector in a subsystem of a GPS satellite due to its natural <span class="hlt">electron</span> <span class="hlt">environment</span>, employing a relatively complex model of the satellite. The capability for survivability analysis of space systems is demonstrated, and results are obtained with and without variance reduction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5379059','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5379059"><span>Plasmonic hot <span class="hlt">electron</span> <span class="hlt">transport</span> drives nano-localized chemistry</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cortés, Emiliano; Xie, Wei; Cambiasso, Javier; Jermyn, Adam S.; Sundararaman, Ravishankar; Narang, Prineha; Schlücker, Sebastian; Maier, Stefan A.</p> <p>2017-01-01</p> <p>Nanoscale localization of electromagnetic fields near metallic nanostructures underpins the fundamentals and applications of plasmonics. The unavoidable energy loss from plasmon decay, initially seen as a detriment, has now expanded the scope of plasmonic applications to exploit the generated hot carriers. However, quantitative understanding of the spatial localization of these hot carriers, akin to electromagnetic near-field maps, has been elusive. Here we spatially map hot-<span class="hlt">electron</span>-driven reduction chemistry with 15 nm resolution as a function of time and electromagnetic field polarization for different plasmonic nanostructures. We combine experiments employing a six-<span class="hlt">electron</span> photo-recycling process that modify the terminal group of a self-assembled monolayer on plasmonic silver nanoantennas, with theoretical predictions from first-principles calculations of non-equilibrium hot-carrier <span class="hlt">transport</span> in these systems. The resulting localization of reactive regions, determined by hot-carrier <span class="hlt">transport</span> from high-field regions, paves the way for improving efficiency in hot-carrier extraction science and nanoscale regio-selective surface chemistry. PMID:28348402</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPCM...29G4002B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPCM...29G4002B"><span><span class="hlt">Electron</span> <span class="hlt">transport</span> in stepped Bi2Se3 thin films</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bauer, S.; Bobisch, C. A.</p> <p>2017-08-01</p> <p>We analyse the <span class="hlt">electron</span> <span class="hlt">transport</span> in a 16 quintuple layer thick stepped Bi2Se3 film grown on Si(1 1 1) by means of scanning tunnelling potentiometry (STP) and multi-point probe measurements. Scanning tunnelling microscopy images reveal that the local structure of the Bi2Se3 film is dominated by terrace steps and domain boundaries. From a microscopic study on the nm scale by STP, we find a mostly linear gradient of the voltage on the Bi2Se3 terraces which is interrupted by voltage drops at the position of the domain boundaries. The voltage drops indicate that the domain boundaries are scatterers for the <span class="hlt">electron</span> <span class="hlt">transport</span>. Macroscopic resistance measurements (2PP and in-line 4PP measurement) on the µm scale support the microscopic results. An additional rotational square 4PP measurement shows an electrical anisotropy of the sheet conductance parallel and perpendicular to the Bi2Se3 steps of about 10%. This is a result of the anisotropic step distribution at the stepped Bi2Se3 surface while domain boundaries are distributed isotropically. The determined value of the conductivity of the Bi2Se3 steps of about 1000 S cm-1 verifies the value of an earlier STP study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1343313','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1343313"><span>ecode - <span class="hlt">Electron</span> <span class="hlt">Transport</span> Algorithm Testing v. 1.0</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Franke, Brian C.; Olson, Aaron J.; Bruss, Donald Eugene; Laub, Thomas W.; Crawford, Martin J; Kenseck, Ronald P.; Prinja, Anil</p> <p>2016-10-05</p> <p>ecode is a Monte Carlo code used for testing algorithms related to <span class="hlt">electron</span> <span class="hlt">transport</span>. The code can read basic physics parameters, such as energy-dependent stopping powers and screening parameters. The code permits simple planar geometries of slabs or cubes. Parallelization consists of domain replication, with work distributed at the start of the calculation and statistical results gathered at the end of the calculation. Some basic routines (such as input parsing, random number generation, and statistics processing) are shared with the Integrated Tiger Series codes. A variety of algorithms for uncertainty propagation are incorporated based on the stochastic collocation and stochastic Galerkin methods. These permit uncertainty only in the total and angular scattering cross sections. The code contains algorithms for simulating stochastic mixtures of two materials. The physics is approximate, ranging from mono-energetic and isotropic scattering to screened Rutherford angular scattering and Rutherford energy-loss scattering (simple <span class="hlt">electron</span> <span class="hlt">transport</span> models). No production of secondary particles is implemented, and no photon physics is implemented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5449976','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5449976"><span>One-Dimensional <span class="hlt">Electron</span> <span class="hlt">Transport</span> Layers for Perovskite Solar Cells</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Thakur, Ujwal K.; Kisslinger, Ryan; Shankar, Karthik</p> <p>2017-01-01</p> <p>The <span class="hlt">electron</span> diffusion length (Ln) is smaller than the hole diffusion length (Lp) in many halide perovskite semiconductors meaning that the use of ordered one-dimensional (1D) structures such as nanowires (NWs) and nanotubes (NTs) as <span class="hlt">electron</span> <span class="hlt">transport</span> layers (ETLs) is a promising method of achieving high performance halide perovskite solar cells (HPSCs). ETLs consisting of oriented and aligned NWs and NTs offer the potential not merely for improved directional charge <span class="hlt">transport</span> but also for the enhanced absorption of incoming light and thermodynamically efficient management of photogenerated carrier populations. The ordered architecture of NW/NT arrays affords superior infiltration of a deposited material making them ideal for use in HPSCs. Photoconversion efficiencies (PCEs) as high as 18% have been demonstrated for HPSCs using 1D ETLs. Despite the advantages of 1D ETLs, there are still challenges that need to be overcome to achieve even higher PCEs, such as better methods to eliminate or passivate surface traps, improved understanding of the hetero-interface and optimization of the morphology (i.e., length, diameter, and spacing of NWs/NTs). This review introduces the general considerations of ETLs for HPSCs, deposition techniques used, and the current research and challenges in the field of 1D ETLs for perovskite solar cells. PMID:28468280</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25071080','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25071080"><span>Dirac model of <span class="hlt">electronic</span> <span class="hlt">transport</span> in graphene antidot barriers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thomsen, M R; Brun, S J; Pedersen, T G</p> <p>2014-08-20</p> <p>In order to use graphene for semiconductor applications, such as transistors with high on/off ratios, a band gap must be introduced into this otherwise semimetallic material. A promising method of achieving a band gap is by introducing nanoscale perforations (antidots) in a periodic pattern, known as a graphene antidot lattice (GAL). A graphene antidot barrier (GAB) can be made by introducing a 1D GAL strip in an otherwise pristine sheet of graphene. In this paper, we will use the Dirac equation (DE) with a spatially varying mass term to calculate the <span class="hlt">electronic</span> <span class="hlt">transport</span> through such structures. Our approach is much more general than previous attempts to use the Dirac equation to calculate scattering of Dirac <span class="hlt">electrons</span> on antidots. The advantage of using the DE is that the computational time is scale invariant and our method may therefore be used to calculate properties of arbitrarily large structures. We show that the results of our Dirac model are in quantitative agreement with tight-binding for hexagonal antidots with armchair edges. Furthermore, for a wide range of structures, we verify that a relatively narrow GAB, with only a few antidots in the unit cell, is sufficient to give rise to a <span class="hlt">transport</span> gap.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvB..95c5430R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvB..95c5430R"><span><span class="hlt">Electronic</span> <span class="hlt">transport</span> in disordered MoS2 nanoribbons</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ridolfi, Emilia; Lima, Leandro R. F.; Mucciolo, Eduardo R.; Lewenkopf, Caio H.</p> <p>2017-01-01</p> <p>We study the <span class="hlt">electronic</span> structure and <span class="hlt">transport</span> properties of zigzag and armchair monolayer molybdenum disulfide nanoribbons using an 11-band tight-binding model that accurately reproduces the material's bulk band structure near the band gap. We study the <span class="hlt">electronic</span> properties of pristine zigzag and armchair nanoribbons, paying particular attention to the edges states that appear within the MoS2 bulk gap. By analyzing both their orbital composition and their local density of states, we find that in zigzag-terminated nanoribbons these states can be localized at a single edge for certain energies independent of the nanoribbon width. We also study the effects of disorder in these systems using the recursive Green's function technique. We show that for the zigzag nanoribbons, the conductance due to the edge states is strongly suppressed by short-range disorder such as vacancies. In contrast, the local density of states still shows edge localization. We also show that long-range disorder has a small effect on the <span class="hlt">transport</span> properties of nanoribbons within the bulk gap energy window.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NatCo...814880C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NatCo...814880C"><span>Plasmonic hot <span class="hlt">electron</span> <span class="hlt">transport</span> drives nano-localized chemistry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cortés, Emiliano; Xie, Wei; Cambiasso, Javier; Jermyn, Adam S.; Sundararaman, Ravishankar; Narang, Prineha; Schlücker, Sebastian; Maier, Stefan A.</p> <p>2017-03-01</p> <p>Nanoscale localization of electromagnetic fields near metallic nanostructures underpins the fundamentals and applications of plasmonics. The unavoidable energy loss from plasmon decay, initially seen as a detriment, has now expanded the scope of plasmonic applications to exploit the generated hot carriers. However, quantitative understanding of the spatial localization of these hot carriers, akin to electromagnetic near-field maps, has been elusive. Here we spatially map hot-<span class="hlt">electron</span>-driven reduction chemistry with 15 nm resolution as a function of time and electromagnetic field polarization for different plasmonic nanostructures. We combine experiments employing a six-<span class="hlt">electron</span> photo-recycling process that modify the terminal group of a self-assembled monolayer on plasmonic silver nanoantennas, with theoretical predictions from first-principles calculations of non-equilibrium hot-carrier <span class="hlt">transport</span> in these systems. The resulting localization of reactive regions, determined by hot-carrier <span class="hlt">transport</span> from high-field regions, paves the way for improving efficiency in hot-carrier extraction science and nanoscale regio-selective surface chemistry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28348402','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28348402"><span>Plasmonic hot <span class="hlt">electron</span> <span class="hlt">transport</span> drives nano-localized chemistry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cortés, Emiliano; Xie, Wei; Cambiasso, Javier; Jermyn, Adam S; Sundararaman, Ravishankar; Narang, Prineha; Schlücker, Sebastian; Maier, Stefan A</p> <p>2017-03-28</p> <p>Nanoscale localization of electromagnetic fields near metallic nanostructures underpins the fundamentals and applications of plasmonics. The unavoidable energy loss from plasmon decay, initially seen as a detriment, has now expanded the scope of plasmonic applications to exploit the generated hot carriers. However, quantitative understanding of the spatial localization of these hot carriers, akin to electromagnetic near-field maps, has been elusive. Here we spatially map hot-<span class="hlt">electron</span>-driven reduction chemistry with 15 nm resolution as a function of time and electromagnetic field polarization for different plasmonic nanostructures. We combine experiments employing a six-<span class="hlt">electron</span> photo-recycling process that modify the terminal group of a self-assembled monolayer on plasmonic silver nanoantennas, with theoretical predictions from first-principles calculations of non-equilibrium hot-carrier <span class="hlt">transport</span> in these systems. The resulting localization of reactive regions, determined by hot-carrier <span class="hlt">transport</span> from high-field regions, paves the way for improving efficiency in hot-carrier extraction science and nanoscale regio-selective surface chemistry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/477761','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/477761"><span><span class="hlt">Electron</span> <span class="hlt">transport</span> in coupled double quantum wells and wires</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Harff, N.E.; Simmons, J.A.; Lyo, S.K.</p> <p>1997-04-01</p> <p>Due to inter-quantum well tunneling, coupled double quantum wells (DQWs) contain an extra degree of <span class="hlt">electronic</span> freedom in the growth direction, giving rise to new <span class="hlt">transport</span> phenomena not found in single <span class="hlt">electron</span> layers. This report describes work done on coupled DQWs subject to inplane magnetic fields B{sub {parallel}}, and is based on the lead author`s doctoral thesis, successfully defended at Oregon State University on March 4, 1997. First, the conductance of closely coupled DQWs in B{sub {parallel}} is studied. B{sub {parallel}}-induced distortions in the dispersion, the density of states, and the Fermi surface are described both theoretically and experimentally, with particular attention paid to the dispersion anticrossing and resulting partial energy gap. Measurements of giant distortions in the effective mass are found to agree with theoretical calculations. Second, the Landau level spectra of coupled DQWs in tilted magnetic fields is studied. The magnetoresistance oscillations show complex beating as Landau levels from the two Fermi surface components cross the Fermi level. A third set of oscillations resulting from magnetic breakdown is observed. A semiclassical calculation of the Landau level spectra is then performed, and shown to agree exceptionally well with the data. Finally, quantum wires and quantum point contacts formed in DQW structures are investigated. Anticrossings of the one-dimensional DQW dispersion curves are predicted to have interesting <span class="hlt">transport</span> effects in these devices. Difficulties in sample fabrication have to date prevented experimental verification. However, recently developed techniques to overcome these difficulties are described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28628028','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28628028"><span><span class="hlt">Electron</span> <span class="hlt">transport</span> in stepped Bi2Se3 thin films.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bauer, S; Bobisch, C A</p> <p>2017-08-23</p> <p>We analyse the <span class="hlt">electron</span> <span class="hlt">transport</span> in a 16 quintuple layer thick stepped Bi2Se3 film grown on Si(1 1 1) by means of scanning tunnelling potentiometry (STP) and multi-point probe measurements. Scanning tunnelling microscopy images reveal that the local structure of the Bi2Se3 film is dominated by terrace steps and domain boundaries. From a microscopic study on the nm scale by STP, we find a mostly linear gradient of the voltage on the Bi2Se3 terraces which is interrupted by voltage drops at the position of the domain boundaries. The voltage drops indicate that the domain boundaries are scatterers for the <span class="hlt">electron</span> <span class="hlt">transport</span>. Macroscopic resistance measurements (2PP and in-line 4PP measurement) on the µm scale support the microscopic results. An additional rotational square 4PP measurement shows an electrical anisotropy of the sheet conductance parallel and perpendicular to the Bi2Se3 steps of about 10%. This is a result of the anisotropic step distribution at the stepped Bi2Se3 surface while domain boundaries are distributed isotropically. The determined value of the conductivity of the Bi2Se3 steps of about 1000 S cm(-1) verifies the value of an earlier STP study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28468280','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28468280"><span>One-Dimensional <span class="hlt">Electron</span> <span class="hlt">Transport</span> Layers for Perovskite Solar Cells.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thakur, Ujwal K; Kisslinger, Ryan; Shankar, Karthik</p> <p>2017-04-29</p> <p>The <span class="hlt">electron</span> diffusion length (Ln) is smaller than the hole diffusion length (Lp) in many halide perovskite semiconductors meaning that the use of ordered one-dimensional (1D) structures such as nanowires (NWs) and nanotubes (NTs) as <span class="hlt">electron</span> <span class="hlt">transport</span> layers (ETLs) is a promising method of achieving high performance halide perovskite solar cells (HPSCs). ETLs consisting of oriented and aligned NWs and NTs offer the potential not merely for improved directional charge <span class="hlt">transport</span> but also for the enhanced absorption of incoming light and thermodynamically efficient management of photogenerated carrier populations. The ordered architecture of NW/NT arrays affords superior infiltration of a deposited material making them ideal for use in HPSCs. Photoconversion efficiencies (PCEs) as high as 18% have been demonstrated for HPSCs using 1D ETLs. Despite the advantages of 1D ETLs, there are still challenges that need to be overcome to achieve even higher PCEs, such as better methods to eliminate or passivate surface traps, improved understanding of the hetero-interface and optimization of the morphology (i.e., length, diameter, and spacing of NWs/NTs). This review introduces the general considerations of ETLs for HPSCs, deposition techniques used, and the current research and challenges in the field of 1D ETLs for perovskite solar cells.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..MARF29007L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..MARF29007L"><span><span class="hlt">Electronic</span> <span class="hlt">transport</span> in graphene sheets in a random magnetic field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lewenkopf, Caio; Burgos, Rhonald; Warnes, Jesus; Lima, Leandro</p> <p>2014-03-01</p> <p>We present a theoretical study of the effect of ripples and strain fields in the <span class="hlt">transport</span> properties of diffusive deposited graphene flakes. Defects in the crystalline structure, adsorbed atomic impurities and charge inhomogeneities at the substrate are believed to be the dominant disorder sources for the <span class="hlt">electronic</span> <span class="hlt">transport</span> in graphene at low temperatures. We show that intrinsic ripples also effect the conductivity, in particular, its quantum corrections. To this end, we analyze recent experimental results on the conductivity of rippled monolayer graphene sheets subjected to a strong magnetic field parallel to the graphene-substrate interface, B∥ [M. B. Lundeberg and J. A. Folk, Phys. Rev. Lett. 105, 146804 (2010)]. In this setting, B∥ gives rise to a random magnetic field normal to graphene sheet, that depends on the local curvature of the smooth disordered ripples. The analysis of the weak localization corrections of the magnetoconductance allows to establish the dependence of <span class="hlt">electronic</span> dephasing rate on the magnitude of the random magnetic field. We compare the results for B∥ with the conductivity and weak localization corrections due to the pseudo-magnetic fields originated by intrinsic ripples and strain fields.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28285094','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28285094"><span>Identifying the molecular functions of <span class="hlt">electron</span> <span class="hlt">transport</span> proteins using radial basis function networks and biochemical properties.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Le, Nguyen-Quoc-Khanh; Nguyen, Trinh-Trung-Duong; Ou, Yu-Yen</p> <p>2017-05-01</p> <p>The <span class="hlt">electron</span> <span class="hlt">transport</span> proteins have an important role in storing and transferring <span class="hlt">electrons</span> in cellular respiration, which is the most proficient process through which cells gather energy from consumed food. According to the molecular functions, the <span class="hlt">electron</span> <span class="hlt">transport</span> chain components could be formed with five complexes with several different <span class="hlt">electron</span> carriers and functions. Therefore, identifying the molecular functions in the <span class="hlt">electron</span> <span class="hlt">transport</span> chain is vital for helping biologists understand the <span class="hlt">electron</span> <span class="hlt">transport</span> chain process and energy production in cells. This work includes two phases for discriminating <span class="hlt">electron</span> <span class="hlt">transport</span> proteins from <span class="hlt">transport</span> proteins and classifying categories of five complexes in <span class="hlt">electron</span> <span class="hlt">transport</span> proteins. In the first phase, the performances from PSSM with AAIndex feature set were successful in identifying <span class="hlt">electron</span> <span class="hlt">transport</span> proteins in <span class="hlt">transport</span> proteins with achieved sensitivity of 73.2%, specificity of 94.1%, and accuracy of 91.3%, with MCC of 0.64 for independent data set. With the second phase, our method can approach a precise model for identifying of five complexes with different molecular functions in <span class="hlt">electron</span> <span class="hlt">transport</span> proteins. The PSSM with AAIndex properties in five complexes achieved MCC of 0.51, 0.47, 0.42, 0.74, and 1.00 for independent data set, respectively. We suggest that our study could be a power model for determining new proteins that belongs into which molecular function of <span class="hlt">electron</span> <span class="hlt">transport</span> proteins. Copyright © 2017 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JCoPh.341..397B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JCoPh.341..397B"><span>Modified Monte Carlo method for study of <span class="hlt">electron</span> <span class="hlt">transport</span> in degenerate <span class="hlt">electron</span> gas in the presence of <span class="hlt">electron-electron</span> interactions, application to graphene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Borowik, Piotr; Thobel, Jean-Luc; Adamowicz, Leszek</p> <p>2017-07-01</p> <p>Standard computational methods used to take account of the Pauli Exclusion Principle into Monte Carlo (MC) simulations of <span class="hlt">electron</span> <span class="hlt">transport</span> in semiconductors may give unphysical results in low field regime, where obtained <span class="hlt">electron</span> distribution function takes values exceeding unity. Modified algorithms were already proposed and allow to correctly account for <span class="hlt">electron</span> scattering on phonons or impurities. Present paper extends this approach and proposes improved simulation scheme allowing including Pauli exclusion principle for <span class="hlt">electron-electron</span> (e-e) scattering into MC simulations. Simulations with significantly reduced computational cost recreate correct values of the <span class="hlt">electron</span> distribution function. Proposed algorithm is applied to study <span class="hlt">transport</span> properties of degenerate <span class="hlt">electrons</span> in graphene with e-e interactions. This required adapting the treatment of e-e scattering in the case of linear band dispersion relation. Hence, this part of the simulation algorithm is described in details.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26927905','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26927905"><span>Physiological Functions of Cyclic <span class="hlt">Electron</span> <span class="hlt">Transport</span> Around Photosystem I in Sustaining Photosynthesis and Plant Growth.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yamori, Wataru; Shikanai, Toshiharu</p> <p>2016-04-29</p> <p>The light reactions in photosynthesis drive both linear and cyclic <span class="hlt">electron</span> <span class="hlt">transport</span> around photosystem I (PSI). Linear <span class="hlt">electron</span> <span class="hlt">transport</span> generates both ATP and NADPH, whereas PSI cyclic <span class="hlt">electron</span> <span class="hlt">transport</span> produces ATP without producing NADPH. PSI cyclic <span class="hlt">electron</span> <span class="hlt">transport</span> is thought to be essential for balancing the ATP/NADPH production ratio and for protecting both photosystems from damage caused by stromal overreduction. Two distinct pathways of cyclic <span class="hlt">electron</span> <span class="hlt">transport</span> have been proposed in angiosperms: a major pathway that depends on the PROTON GRADIENT REGULATION 5 (PGR5) and PGR5-LIKE PHOTOSYNTHETIC PHENOTYPE 1 (PGRL1) proteins, which are the target site of antimycin A, and a minor pathway mediated by the chloroplast NADH dehydrogenase-like (NDH) complex. Recently, the regulation of PSI cyclic <span class="hlt">electron</span> <span class="hlt">transport</span> has been recognized as essential for photosynthesis and plant growth. In this review, we summarize the possible functions and importance of the two pathways of PSI cyclic <span class="hlt">electron</span> <span class="hlt">transport</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..GECMW6035D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..GECMW6035D"><span>Third order <span class="hlt">transport</span> coefficients for <span class="hlt">electrons</span> and positrons in gases</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dujko, Sasa; Simonovic, Ilija; White, Ronald; Petrovic, Zoran</p> <p>2016-09-01</p> <p>Third order <span class="hlt">transport</span> coefficients (the skewness tensor) of the <span class="hlt">electron</span> and positron swarms, in atomic and molecular gases, are investigated. The knowledge of the skewness tensor is necessary for the conversion of the hydrodynamic <span class="hlt">transport</span> coefficients to the arrival time and steady-state Townsend <span class="hlt">transport</span> data as well as for the determination of the deviations of the spatial density profiles from an ideal Gaussian. In this work, we investigate the structure and symmetries along individual elements of the skewness tensor by the group projector method. Individual components of the skewness tensor are calculated using a Monte Carlo simulation technique and multi term theory for solving the Boltzmann equation. Results obtained by these two methods are in excellent agreement. We extend previous studies by considering the sensitivity of the skewness components to explicit and implicit effects of non-conservative collisions, post-ionization energy partitioning, and inelastic collisions. The errors of the two term approximation for solving the Boltzmann equation are highlighted. We also investigate the influence of a magnetic field on the skewness tensor in varying configurations of electric and magnetic fields. Among many interesting points, we have observed a strong correlation between the skewness and diffusion.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..MARF30008C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..MARF30008C"><span><span class="hlt">Electronic</span> <span class="hlt">transport</span> in graphene ribbons with a Gausssian deformation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carrillo, Ramon; Faria, Daiara; Latgé, Andrea; Mireles, Francisco; Sandler, Nancy</p> <p>2014-03-01</p> <p>The coupling of geometrical and <span class="hlt">electronic</span> properties is a promising avenue to engineer conduction properties in graphene. Confinement added to strain allows for interplay of different <span class="hlt">transport</span> mechanisms with potential device applications. In particular, strain-predicted to produce localized states similar to those in an external magnetic field-can be tailored for desired <span class="hlt">transport</span> properties. To investigate specific strain signatures on <span class="hlt">transport</span> in confined geometries, we focus on graphene nanoribbons with different edge terminations and circularly symmetric deformations. In particular, we study nanoribbons with an inhomogeneous, out of plane Gaussian bump deformation, connected to reservoirs, with and without external magnetic field. We use the tight-binding approximation with the deformation described by elasticity theory. Using the recursive Green function algorithm, we calculate the local density of states and obtain the Landauer conductance. An enhancement of the density of states in the deformed region, similar to the one appearing with constant fields in confined regions is observed. We show how these confined states give rise to peculiar features in the emerging Landau levels and discuss their effect on the overall conductance. Supported by NSF-MWN/CIAM, NSF-PIRE and CONACyT (México).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhRvB..90c5445F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhRvB..90c5445F"><span>Real-space method for highly parallelizable <span class="hlt">electronic</span> <span class="hlt">transport</span> calculations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Feldman, Baruch; Seideman, Tamar; Hod, Oded; Kronik, Leeor</p> <p>2014-07-01</p> <p>We present a real-space method for first-principles nanoscale <span class="hlt">electronic</span> <span class="hlt">transport</span> calculations. We use the nonequilibrium Green's function method with density functional theory and implement absorbing boundary conditions (ABCs, also known as complex absorbing potentials, or CAPs) to represent the effects of the semi-infinite leads. In real space, the Kohn-Sham Hamiltonian matrix is highly sparse. As a result, the <span class="hlt">transport</span> problem parallelizes naturally and can scale favorably with system size, enabling the computation of conductance in relatively large molecular junction models. Our use of ABCs circumvents the demanding task of explicitly calculating the leads' self-energies from surface Green's functions, and is expected to be more accurate than the use of the jellium approximation. In addition, we take advantage of the sparsity in real space to solve efficiently for the Green's function over the entire energy range relevant to low-bias <span class="hlt">transport</span>. We illustrate the advantages of our method with calculations on several challenging test systems and find good agreement with reference calculation results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15148017','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15148017"><span>Assessing reference staff competency in the <span class="hlt">electronic</span> <span class="hlt">environment</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Munson, Kurt I; Walton, Linda J</p> <p>2004-01-01</p> <p>This paper shows how the Galter Health Sciences Library of Northwestern University's Feinberg School of Medicine developed and implemented a program to assess reference staff competencies for assisting users in the <span class="hlt">electronic</span> <span class="hlt">environment</span> after completing a new training program. The first phase was a year-long assessment of reference questions to identify the types of questions received at the desk. Next, a training program for reference was developed and implemented with an emphasis on answering the most common questions identified such as remote access, access privileges, holdings information, and database searching. The program included individualized instruction on library policies, <span class="hlt">electronic</span> resources, access restrictions, and troubleshooting. The next phase was to create instruments to test staff competencies in answering questions after training. Based on the scores, additional training was individualized and provided to the appropriate staff member to enhance their skills where needed. The training system that was developed has proven to be effective as most staff scored better than 92% on initial testing. As a result, library management can be certain that users' questions are being answered correctly and that the staff has the skills required to work in an <span class="hlt">electronic</span> <span class="hlt">environment</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21837726','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21837726"><span>Density functional theory study on <span class="hlt">electron</span> and hole <span class="hlt">transport</span> properties of organic pentacene derivatives with <span class="hlt">electron</span>-withdrawing substituent.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chai, Shuo; Wen, Shu-Hao; Huang, Jin-Dou; Han, Ke-Li</p> <p>2011-11-30</p> <p>Attaching <span class="hlt">electron</span>-withdrawing substituent to organic conjugated molecules is considered as an effective method to produce n-type and ambipolar <span class="hlt">transport</span> materials. In this work, we use density functional theory calculations to investigate the <span class="hlt">electron</span> and hole <span class="hlt">transport</span> properties of pentacene (PENT) derivatives after substituent and simulate the angular resolution anisotropic mobility for both <span class="hlt">electron</span> and hole <span class="hlt">transport</span>. Our results show that adding <span class="hlt">electron</span>-withdrawing substituents can lower the energy level of lowest unoccupied molecular orbital (LUMO) and increase <span class="hlt">electron</span> affinity, which are beneficial to the <span class="hlt">electron</span> injection and ambient stability of the material. Also the LUMO <span class="hlt">electronic</span> couplings for <span class="hlt">electron</span> <span class="hlt">transport</span> in these pentacene derivatives can achieve up to a hundred meV which promises good <span class="hlt">electron</span> <span class="hlt">transport</span> mobility, although adding <span class="hlt">electron</span>-withdrawing groups will introduce the increase of <span class="hlt">electron</span> transfer reorganization energy. The final results of our angular resolution anisotropic mobility simulations show that the <span class="hlt">electron</span> mobility of these pentacene derivatives can get to several cm(2) V(-1) s(-1), but it is important to control the orientation of the organic material relative to the device channel to obtain the highest <span class="hlt">electron</span> mobility. Our investigation provide detailed information to assist in the design of n-type and ambipolar organic <span class="hlt">electronic</span> materials with high mobility performance. Copyright © 2011 Wiley Periodicals, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006PhDT.......246M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006PhDT.......246M"><span>Low-dimensional <span class="hlt">electron</span> <span class="hlt">transport</span> in mesoscopic semiconductor devices</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martin, Theodore Peyton</p> <p></p> <p>Recent advances in solid state materials engineering have led to mesoscopic devices with feature sizes that approach the fundamental quantum wavelength of charge carriers in the solid, allowing for the experimental observation of quantum interference. By confining carriers to a single quantum state in one or more dimensions, the degrees of freedom for charge <span class="hlt">transport</span> can be reduced to achieve new device functionality. This dissertation focuses on mesoscopic <span class="hlt">electron</span> billiards that combine the aspects of zero, one, and two-dimensional <span class="hlt">transport</span> into one system. Low-temperature measurement of billiards fabricated within a relatively defect-free semiconductor heterostructure results in ballistic <span class="hlt">transport</span>, where the <span class="hlt">electron</span> waves follow classical trajectories and the confining walls play a major role in determining the <span class="hlt">electron</span> interference. Billiards have been traditionally formed by applying a bias to patterned surface gates atop an AlGaAs/GaAs heterostructure. Within this system, fractal fluctuations in the billiard conductance are observed as a function of an applied external magnetic field. These fluctuations are tied to quantum interference via an empirical parameter that describes the resolution of energy levels within the billiard. To investigate whether fractal fluctuations are a robust phenomenon intrinsic to billiard-like structures, this study centers on billiards defined by etching walls into a GaInAs/InP heterostructure, departing from the traditional system in both the type of confinement and material system used. It is expected that etched walls will provide a steeper confinement profile leading to well-defined device shapes. Conductance measurements through the one-dimensional leads that couple <span class="hlt">electrons</span> into the billiard are utilized in combination with a self-consistent Schrodinger/Poisson solution to demonstrate a steeper confinement potential. Experiments are also carried out to determine whether fractal fluctuations persist when billiards are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.B53C0546K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.B53C0546K"><span>Electrode Cultivation and Interfacial <span class="hlt">Electron</span> <span class="hlt">Transport</span> in Subsurface Microorganisms</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Karbelkar, A. A.; Jangir, Y.; Reese, B. K.; Wanger, G.; Anderson, C.; El-Naggar, M.; Amend, J.</p> <p>2016-12-01</p> <p>Continental subsurface <span class="hlt">environments</span> can present significant energetic challenges to the resident microorganisms. While these <span class="hlt">environments</span> are geologically diverse, potentially allowing energy harvesting by microorganisms that catalyze redox reactions, many of the abundant <span class="hlt">electron</span> donors and acceptors are insoluble and therefore not directly bioavailable. Microbes can use extracellular <span class="hlt">electron</span> transfer (EET) as a metabolic strategy to interact with redox active surfaces. This process can be mimicked on electrode surfaces and hence can lead to enrichment and quantification of subsurface microorganisms A primary bioelectrochemical enrichment with different oxidizing and reducing potentials set up in a single bioreactor was applied in situ to subsurface microorganisms residing in iron oxide rich deposits in the Sanford Underground Research Facility. Secondary enrichment revealed a plethora of classified and unclassified subsurface microbiota on both oxidizing and reducing potentials. From this enrichment, we have isolated a Gram-positive Bacillus along with Gram-negative Cupriavidus and Anaerospora strains (as electrode reducers) and Comamonas (as an electrode oxidizer). The Bacillus and Comamonas isolates were subjected to a detailed electrochemical characterization in half-reactors at anodic and cathodic potentials, respectively. An increase in cathodic current upon inoculation and cyclic voltammetry measurements confirm the hypothesis that Comamonas is capable of <span class="hlt">electron</span> uptake from electrodes. In addition, measurements of Bacillus on anodes hint towards novel mechanisms that allow EET from Gram-positive bacteria. This study suggests that electrochemical approaches are well positioned to dissect such extracellular interactions that may be prevalent in the subsurface, while using physical electrodes to emulate the microhabitats, redox and geochemical gradients, and the spatially dependent interspecies interactions encountered in the subsurface. Electrochemical</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110015809','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110015809"><span>Modeling Ionosphere <span class="hlt">Environments</span>: Creating an ISS <span class="hlt">Electron</span> Density Tool</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gurgew, Danielle N.; Minow, Joseph I.</p> <p>2011-01-01</p> <p>The International Space Station (ISS) maintains an altitude typically between 300 km and 400 km in low Earth orbit (LEO) which itself is situated in the Earth's ionosphere. The ionosphere is a region of partially ionized gas (plasma) formed by the photoionization of neutral atoms and molecules in the upper atmosphere of Earth. It is important to understand what <span class="hlt">electron</span> density the spacecraft is/will be operating in because the ionized gas along the ISS orbit interacts with the electrical power system resulting in charging of the vehicle. One instrument that is already operational onboard the ISS with a goal of monitoring <span class="hlt">electron</span> density, <span class="hlt">electron</span> temperature, and ISS floating potential is the Floating Potential Measurement Unit (FPMU). Although this tool is a valuable addition to the ISS, there are limitations concerning the data collection periods. The FPMU uses the Ku band communication frequency to transmit data from orbit. Use of this band for FPMU data runs is often terminated due to necessary observation of higher priority Extravehicular Activities (EVAs) and other operations on ISS. Thus, large gaps are present in FPMU data. The purpose of this study is to solve the issue of missing environmental data by implementing a secondary <span class="hlt">electron</span> density data source, derived from the COSMIC satellite constellation, to create a model of ISS orbital <span class="hlt">environments</span>. Extrapolating data specific to ISS orbital altitudes, we model the ionospheric <span class="hlt">electron</span> density along the ISS orbit track to supply a set of data when the FPMU is unavailable. This computer model also provides an additional new source of <span class="hlt">electron</span> density data that is used to confirm FPMU is operating correctly and supplements the original environmental data taken by FPMU.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23331168','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23331168"><span>When <span class="hlt">electron</span> transfer meets <span class="hlt">electron</span> <span class="hlt">transport</span> in redox-active molecular nanojunctions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Janin, Marion; Ghilane, Jalal; Lacroix, Jean-Christophe</p> <p>2013-02-13</p> <p>A scanning electrochemical microscope (SECM) was used to arrange two microelectrodes face-to-face separated by a micrometric gap. Polyaniline (PANI) was deposited electrochemically from the SECM tip side until it bridged the two electrodes. The junctions obtained were characterized by following the current through the PANI as a function of its electrochemical potential measured versus a reference electrode acting as a gate electrode in a solid-state transistor. PANI nanojunctions showed conductances below 100 nS in the oxidized state, indicating control of the charge <span class="hlt">transport</span> within the whole micrometric gap by a limited number of PANI wires. The SECM configuration makes it possible to observe in the same experiment and in the same current range the <span class="hlt">electron</span>-transfer and <span class="hlt">electron-transport</span> processes. These two phenomena are distinguished here and characterized by following the variation of the current with the bias voltage and the scan rate. The <span class="hlt">electron</span>-transfer current changes with the scan rate, while the charge-<span class="hlt">transport</span> current varies with the bias voltage. Finally, despite the initially micrometric gap, a junction where the conductance is controlled by a single oligoaniline strand is achieved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/15002024','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/15002024"><span>Developing Intelligent <span class="hlt">Transportation</span> Systems in an Integrated Systems Analysis <span class="hlt">Environment</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Aceves, S M; Paddack, E</p> <p>2002-01-15</p> <p>We are working on developing an Integrated Systems Analysis <span class="hlt">Environment</span> (ISAE) for application to analysis and optimization of Intelligent <span class="hlt">Transportation</span> Systems (ITS). ISAE is based on the concept of Co-simulation, which allows the modeling of complex systems with extreme flexibility. Co-simulation allows the development of virtual ITS systems that can be analyzed and optimized as an overall integrated system. The virtual ITS system is defined by selecting different components from a component library. System component models can be written in multiple programming languages running on different computer platforms. At the same time, ISAE provides full protection for proprietary models. Co-simulation is a cost-effective alternative to competing methodologies, such as developing a translator or selecting a single programming language for all system components. Co-simulation has been recently demonstrated using an example of an automotive system. The demonstration was successfully performed. The paper describes plans on how to implement ISAE and Co-simulation to ITS, and the great advantages that this implementation would represent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DFDL30004G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DFDL30004G"><span>Energy and water vapor <span class="hlt">transport</span> in a turbulent stratified <span class="hlt">environment</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gallana, Luca; de Santi, Francesca; Iovieno, Michele; Richiardone, Renzo; Tordella, Daniela</p> <p>2015-11-01</p> <p>We present direct numerical simulations about the <span class="hlt">transport</span> of kinetic energy and unsaturated water vapor across a thin layer which separates two decaying turbulent flows with different energy. This interface lies in a shearless stratified <span class="hlt">environment</span> modeled by means of Boussinesq's approximation. Water vapor is treated as a passive scalar (Kumar et al. 2014). Initial conditions have Fr2 between 0.64 and 64 (stable case) and between -3.2 and -19 (unstable case) and Reλ = 250 . Dry air is in the lower half of the domain and has a higher turbulent energy, seven times higher than the energy of moist air in the upper half. In the early stage of evolution, as long as | F r2 | > 1 , stratification plays a minor role and the flows follows closely neutral stratification mixing. As the buoyancy terms grows, Fr2 ~ O (1) , the mixing process deeply changes. A stable stratification generates a separation layer which blocks the entrainment of dry air into the moist one, characterized by a relative increment of the turbulent dissipation rate compared to the local turbulent energy. On the contrary, an unstable stratification sligthy enhances the entrainment. Growth-decay of energy and mixing layer thichness are discussed and compared with laboratory and numerical experiments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..MARH13012H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..MARH13012H"><span>Hot <span class="hlt">electron</span> spin <span class="hlt">transport</span> in C60 fullerene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hueso, Luis Eduardo; Gobbi, Marco; Bedoya-Pinto, Amilcar; Golmar, Federico; Llopis, Roger; Casanova, Felix</p> <p>2012-02-01</p> <p>Carbon-based molecular materials are interesting for spin <span class="hlt">transport</span> application mainly due to their small sources of spin relaxation [1]. However, spin coherence lengths reported in many molecular films do not exceed a few tens of nanometers [2]. In this work we will present results showing how hot spin-polarized <span class="hlt">electrons</span> injected well above the Fermi level in C60 fullerene films travel coherently for hundreds of nanometers. We fabricated hot-<span class="hlt">electron</span> vertical transistors, in which the current created across an Al/Al2O3 junction is polarized by a metallic Co/Cu/Py spin valve trilayer and subsequently injected in the molecular thin film. This geometry allows us to determine the energy level alignment at each interface between different materials. Moreover, the collector magnetocurrent excess 85%, even for C60 films thicknesses of 300 nm. We believe these results show the importance of hot spin-polarized <span class="hlt">electron</span> injection and propagation in molecular materials. [1] V. Dediu, L.E. Hueso, I. Bergenti, C. Taliani, Nature Mater. 8, 707 (2009) [2] M. Gobbi, F. Golmar, R. Llopis, F. Casanova, L.E. Hueso, Adv. Mater. 23, 1609 (2011)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21639513','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21639513"><span>Integrated <span class="hlt">electronic</span> <span class="hlt">transport</span> and thermometry at milliKelvin temperatures and in strong magnetic fields.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Samkharadze, N; Kumar, A; Manfra, M J; Pfeiffer, L N; West, K W; Csáthy, G A</p> <p>2011-05-01</p> <p>We fabricated a He-3 immersion cell for <span class="hlt">transport</span> measurements of semiconductor nanostructures at ultra low temperatures and in strong magnetic fields. We have a new scheme of field-independent thermometry based on quartz tuning fork Helium-3 viscometry which monitors the local temperature of the sample's <span class="hlt">environment</span> in real time. The operation and measurement circuitry of the quartz viscometer is described in detail. We provide evidence that the temperature of two-dimensional <span class="hlt">electron</span> gas confined to a GaAs quantum well follows the temperature of the quartz viscometer down to 4 mK.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22062328','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22062328"><span>Integrated <span class="hlt">electronic</span> <span class="hlt">transport</span> and thermometry at milliKelvin temperatures and in strong magnetic fields</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Samkharadze, N.; Kumar, A.; Csathy, G. A.; Manfra, M. J.; Pfeiffer, L. N.; West, K. W.</p> <p>2011-05-15</p> <p>We fabricated a He-3 immersion cell for <span class="hlt">transport</span> measurements of semiconductor nanostructures at ultra low temperatures and in strong magnetic fields. We have a new scheme of field-independent thermometry based on quartz tuning fork Helium-3 viscometry which monitors the local temperature of the sample's <span class="hlt">environment</span> in real time. The operation and measurement circuitry of the quartz viscometer is described in detail. We provide evidence that the temperature of two-dimensional <span class="hlt">electron</span> gas confined to a GaAs quantum well follows the temperature of the quartz viscometer down to 4 mK.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhCS.720a2046D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhCS.720a2046D"><span>Parallel processing implementation for the coupled <span class="hlt">transport</span> of photons and <span class="hlt">electrons</span> using OpenMP</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Doerner, Edgardo</p> <p>2016-05-01</p> <p>In this work the use of OpenMP to implement the parallel processing of the Monte Carlo (MC) simulation of the coupled <span class="hlt">transport</span> for photons and <span class="hlt">electrons</span> is presented. This implementation was carried out using a modified EGSnrc platform which enables the use of the Microsoft Visual Studio 2013 (VS2013) <span class="hlt">environment</span>, together with the developing tools available in the Intel Parallel Studio XE 2015 (XE2015). The performance study of this new implementation was carried out in a desktop PC with a multi-core CPU, taking as a reference the performance of the original platform. The results were satisfactory, both in terms of scalability as parallelization efficiency.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/7030210','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/7030210"><span>Severe shock and vibration <span class="hlt">environments</span> for <span class="hlt">electronic</span> components</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Martinez, D.R.</p> <p>1990-01-01</p> <p><span class="hlt">Electronic</span> components used in system applications must be qualified to mechanical shock and vibration <span class="hlt">environments</span>. Often these <span class="hlt">environments</span> are severe, requiring the development and use of special test techniques and procedures. Environmental specifications are based upon analytical model predictions and measured test data. Test specifications are determined after careful consideration of simulation techniques, input levels, dynamic behavior of the test fixturing, as well as an assessment of the degree of conservatism imposed by the specification and testing procedures. The process of determining component shock and vibration specifications is discussed, beginning with the initial description of system and subsystem level <span class="hlt">environments</span>, and concluding with component level test specifications. Included is a discussion of the difference between environmental specifications and test specifications, and the instrumentation/measurement problems associated with obtaining valid field measurements for severe shock data. The role of finite element analysis in predicting the dynamic structural response of components is also explained. Shock data analysis techniques are described including both time-domain and frequency-domain characterizations of the data. The resonant plate shock testing technique for simulating severe shock <span class="hlt">environments</span> is presented, including difficulties that arise in practical applications. 18 refs., 10 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20110008233&hterms=proton&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dproton','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20110008233&hterms=proton&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dproton"><span>A Deterministic <span class="hlt">Electron</span>, Photon, Proton and Heavy Ion Radiation <span class="hlt">Transport</span> Suite for the Study of the Jovian System</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Norman, Ryan B.; Badavi, Francis F.; Blattnig, Steve R.; Atwell, William</p> <p>2011-01-01</p> <p>A deterministic suite of radiation <span class="hlt">transport</span> codes, developed at NASA Langley Research Center (LaRC), which describe the <span class="hlt">transport</span> of <span class="hlt">electrons</span>, photons, protons, and heavy ions in condensed media is used to simulate exposures from spectral distributions typical of <span class="hlt">electrons</span>, protons and carbon-oxygen-sulfur (C-O-S) trapped heavy ions in the Jovian radiation <span class="hlt">environment</span>. The particle <span class="hlt">transport</span> suite consists of a coupled <span class="hlt">electron</span> and photon deterministic <span class="hlt">transport</span> algorithm (CEPTRN) and a coupled light particle and heavy ion deterministic <span class="hlt">transport</span> algorithm (HZETRN). The primary purpose for the development of the <span class="hlt">transport</span> suite is to provide a means for the spacecraft design community to rapidly perform numerous repetitive calculations essential for <span class="hlt">electron</span>, proton and heavy ion radiation exposure assessments in complex space structures. In this paper, the radiation <span class="hlt">environment</span> of the Galilean satellite Europa is used as a representative boundary condition to show the capabilities of the <span class="hlt">transport</span> suite. While the <span class="hlt">transport</span> suite can directly access the output <span class="hlt">electron</span> spectra of the Jovian <span class="hlt">environment</span> as generated by the Jet Propulsion Laboratory (JPL) Galileo Interim Radiation <span class="hlt">Electron</span> (GIRE) model of 2003; for the sake of relevance to the upcoming Europa Jupiter System Mission (EJSM), the 105 days at Europa mission fluence energy spectra provided by JPL is used to produce the corresponding dose-depth curve in silicon behind an aluminum shield of 100 mils ( 0.7 g/sq cm). The <span class="hlt">transport</span> suite can also accept ray-traced thickness files from a computer-aided design (CAD) package and calculate the total ionizing dose (TID) at a specific target point. In that regard, using a low-fidelity CAD model of the Galileo probe, the <span class="hlt">transport</span> suite was verified by comparing with Monte Carlo (MC) simulations for orbits JOI--J35 of the Galileo extended mission (1996-2001). For the upcoming EJSM mission with a potential launch date of 2020, the <span class="hlt">transport</span> suite is used to compute</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20110008233&hterms=low+dose+radiation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dlow%2Bdose%2Bradiation','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20110008233&hterms=low+dose+radiation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dlow%2Bdose%2Bradiation"><span>A Deterministic <span class="hlt">Electron</span>, Photon, Proton and Heavy Ion Radiation <span class="hlt">Transport</span> Suite for the Study of the Jovian System</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Norman, Ryan B.; Badavi, Francis F.; Blattnig, Steve R.; Atwell, William</p> <p>2011-01-01</p> <p>A deterministic suite of radiation <span class="hlt">transport</span> codes, developed at NASA Langley Research Center (LaRC), which describe the <span class="hlt">transport</span> of <span class="hlt">electrons</span>, photons, protons, and heavy ions in condensed media is used to simulate exposures from spectral distributions typical of <span class="hlt">electrons</span>, protons and carbon-oxygen-sulfur (C-O-S) trapped heavy ions in the Jovian radiation <span class="hlt">environment</span>. The particle <span class="hlt">transport</span> suite consists of a coupled <span class="hlt">electron</span> and photon deterministic <span class="hlt">transport</span> algorithm (CEPTRN) and a coupled light particle and heavy ion deterministic <span class="hlt">transport</span> algorithm (HZETRN). The primary purpose for the development of the <span class="hlt">transport</span> suite is to provide a means for the spacecraft design community to rapidly perform numerous repetitive calculations essential for <span class="hlt">electron</span>, proton and heavy ion radiation exposure assessments in complex space structures. In this paper, the radiation <span class="hlt">environment</span> of the Galilean satellite Europa is used as a representative boundary condition to show the capabilities of the <span class="hlt">transport</span> suite. While the <span class="hlt">transport</span> suite can directly access the output <span class="hlt">electron</span> spectra of the Jovian <span class="hlt">environment</span> as generated by the Jet Propulsion Laboratory (JPL) Galileo Interim Radiation <span class="hlt">Electron</span> (GIRE) model of 2003; for the sake of relevance to the upcoming Europa Jupiter System Mission (EJSM), the 105 days at Europa mission fluence energy spectra provided by JPL is used to produce the corresponding dose-depth curve in silicon behind an aluminum shield of 100 mils ( 0.7 g/sq cm). The <span class="hlt">transport</span> suite can also accept ray-traced thickness files from a computer-aided design (CAD) package and calculate the total ionizing dose (TID) at a specific target point. In that regard, using a low-fidelity CAD model of the Galileo probe, the <span class="hlt">transport</span> suite was verified by comparing with Monte Carlo (MC) simulations for orbits JOI--J35 of the Galileo extended mission (1996-2001). For the upcoming EJSM mission with a potential launch date of 2020, the <span class="hlt">transport</span> suite is used to compute</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22262617','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22262617"><span><span class="hlt">Electron-electron</span> interaction, weak localization and spin valve effect in vertical-<span class="hlt">transport</span> graphene devices</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Long, Mingsheng; Gong, Youpin; Wei, Xiangfei; Zhu, Chao; Xu, Jianbao; Liu, Ping; Guo, Yufen; Li, Weiwei; Liu, Liwei; Liu, Guangtong</p> <p>2014-04-14</p> <p>We fabricated a vertical structure device, in which graphene is sandwiched between two asymmetric ferromagnetic electrodes. The measurements of <span class="hlt">electron</span> and spin <span class="hlt">transport</span> were performed across the combined channels containing the vertical and horizontal components. The presence of <span class="hlt">electron-electron</span> interaction (EEI) was found not only at low temperatures but also at moderate temperatures up to ∼120 K, and EEI dominates over weak localization (WL) with and without applying magnetic fields perpendicular to the sample plane. Moreover, spin valve effect was observed when magnetic filed is swept at the direction parallel to the sample surface. We attribute the EEI and WL surviving at a relatively high temperature to the effective suppress of phonon scattering in the vertical device structure. The findings open a way for studying quantum correlation at relatively high temperature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006JChPh.124c4708J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006JChPh.124c4708J"><span>A generalized quantum chemical approach for elastic and inelastic <span class="hlt">electron</span> <span class="hlt">transports</span> in molecular <span class="hlt">electronics</span> devices</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jiang, Jun; Kula, Mathias; Luo, Yi</p> <p>2006-01-01</p> <p>A generalized quantum chemical approach for <span class="hlt">electron</span> <span class="hlt">transport</span> in molecular devices is developed. It allows one to treat devices where the metal electrodes and the molecule are either chemically or physically bonded on equal footing. An extension to include the vibration motions of the molecule has also been implemented which has produced the inelastic <span class="hlt">electron</span>-tunneling spectroscopy of molecular <span class="hlt">electronics</span> devices with unprecedented accuracy. Important information about the structure of the molecule and of metal-molecule contacts that are not accessible in the experiment are revealed. The calculated current-voltage (I-V) characteristics of different molecular devices, including benzene-1,4-dithiolate, octanemonothiolate [H(CH2)8S], and octanedithiolate [S(CH2)8S] bonded to gold electrodes, are in very good agreement with experimental measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22482256','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22482256"><span>Density-dependent <span class="hlt">electron</span> <span class="hlt">transport</span> and precise modeling of GaN high <span class="hlt">electron</span> mobility transistors</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bajaj, Sanyam Shoron, Omor F.; Park, Pil Sung; Krishnamoorthy, Sriram; Akyol, Fatih; Hung, Ting-Hsiang; Reza, Shahed; Chumbes, Eduardo M.; Khurgin, Jacob; Rajan, Siddharth</p> <p>2015-10-12</p> <p>We report on the direct measurement of two-dimensional sheet charge density dependence of <span class="hlt">electron</span> <span class="hlt">transport</span> in AlGaN/GaN high <span class="hlt">electron</span> mobility transistors (HEMTs). Pulsed IV measurements established increasing <span class="hlt">electron</span> velocities with decreasing sheet charge densities, resulting in saturation velocity of 1.9 × 10{sup 7 }cm/s at a low sheet charge density of 7.8 × 10{sup 11 }cm{sup −2}. An optical phonon emission-based <span class="hlt">electron</span> velocity model for GaN is also presented. It accommodates stimulated longitudinal optical (LO) phonon emission which clamps the <span class="hlt">electron</span> velocity with strong <span class="hlt">electron</span>-phonon interaction and long LO phonon lifetime in GaN. A comparison with the measured density-dependent saturation velocity shows that it captures the dependence rather well. Finally, the experimental result is applied in TCAD-based device simulator to predict DC and small signal characteristics of a reported GaN HEMT. Good agreement between the simulated and reported experimental results validated the measurement presented in this report and established accurate modeling of GaN HEMTs.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21180303','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21180303"><span>Correlation between <span class="hlt">Electron</span> <span class="hlt">Transport</span> and Shear Alfven Activity in the National Spherical Torus Experiment</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Stutman, D.; Delgado-Aparicio, L.; Finkenthal, M.; Tritz, K.; Gorelenkov, N.; Fredrickson, E.; Kaye, S.; Mazzucato, E.</p> <p>2009-03-20</p> <p>We report the observation of a correlation between shear Alfven eigenmode activity and <span class="hlt">electron</span> <span class="hlt">transport</span> in plasma regimes where the <span class="hlt">electron</span> temperature gradient is flat, and thus the drive for temperature gradient microinstabilities is absent. Plasmas having rapid central <span class="hlt">electron</span> <span class="hlt">transport</span> show intense, broadband global Alfven eigenmode (GAE) activity in the 0.5-1.1 MHz range, while plasmas with low <span class="hlt">transport</span> are essentially GAE-free. The first theoretical assessment of a GAE-<span class="hlt">electron</span> <span class="hlt">transport</span> connection indicates that overlapping modes can resonantly couple to the bulk thermal <span class="hlt">electrons</span> and induce their stochastic diffusion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/984468','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/984468"><span>Anomalous <span class="hlt">Electron</span> <span class="hlt">Transport</span> Due to Multiple High Frequency Beam Ion Driven Alfven Eigenmode</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gorelenkov, N. N.; Stutman, D.; Tritz, K.; Boozer, A.; Delgardo-Aparicio, L.; Fredrickson, E.; Kaye, S.; White, R.</p> <p>2010-07-13</p> <p>We report on the simulations of recently observed correlations of the core <span class="hlt">electron</span> <span class="hlt">transport</span> with the sub-thermal ion cyclotron frequency instabilities in low aspect ratio plasmas of the National Spherical Torus Experiment (NSTX). In order to model the <span class="hlt">electron</span> <span class="hlt">transport</span> of the guiding center code ORBIT is employed. A spectrum of test functions of multiple core localized Global shear Alfven Eigenmode (GAE) instabilities based on a previously developed theory and experimental observations is used to examine the <span class="hlt">electron</span> <span class="hlt">transport</span> properties. The simulations exhibit thermal <span class="hlt">electron</span> <span class="hlt">transport</span> induced by <span class="hlt">electron</span> drift orbit stochasticity in the presence of multiple core localized GAE.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhyE...43.1655S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhyE...43.1655S"><span><span class="hlt">Electronic</span> <span class="hlt">transport</span> characteristics in silicon nanotube field-effect transistors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shan, Guangcun; Wang, Yu; Huang, Wei</p> <p>2011-07-01</p> <p>The successful synthesis of silicon nanotubes (SiNTs) has been reported, making these nanostructures a new novel candidate for future nanodevices. By self-consistently solving the Poisson equations using the non-equilibrium Green's function (NEGF) formalism, we investigate the <span class="hlt">electronic</span> <span class="hlt">transport</span> and the role of gate bias in affecting the drive current of single-walled silicon nanotube (SW-SiNT) field-effect transistors (FETs). By comparison of a SW-CNT FET, it is found that the SW-SiNT with a high- k HfO gate oxide is a promising candidate for nanotube transistor with better performance. The results discussed here would serve as a versatile and powerful guideline for future experimental studies of SW-SiNT-based transistor with the purpose of exploring device application for nanoelectronics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22606675','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22606675"><span>Effect of doping on the <span class="hlt">electron</span> <span class="hlt">transport</span> in polyfluorene</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bajpai, Manisha; Srivastava, Ritu; Dhar, Ravindra; Tiwari, R. S.</p> <p>2016-05-06</p> <p>In this paper, <span class="hlt">electron</span> <span class="hlt">transport</span> of pure and DMC doped polyfluorne (PF) films have been studied at various doping concentrations. Pure films show space charge limited conduction with field and temperature dependent mobility. The J–V characteristics of doped PF were ohmic at low voltages due to thermally released carriers from dopant states. At higher voltages the current density increases nonlinearly due to field dependent mobility and carrier concentration thereby filling of tail states of HOMO of the host. The conductivity of doped films were analyzed using the Unified Gaussian Disorder Model (UGDM). The carrier concentration obtained from the fitting show a non-linear dependence on doping concentration which may be due to a combined effect of thermally activated carrier generation and increased carrier mobility.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EPJB...89..191Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EPJB...89..191Z"><span><span class="hlt">Electronic</span> <span class="hlt">transport</span> properties of a quinone-based molecular switch</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zheng, Ya-Peng; Bian, Bao-An; Yuan, Pei-Pei</p> <p>2016-09-01</p> <p>In this paper, we carried out first-principles calculations based on density functional theory and non-equilibrium Green's function to investigate the <span class="hlt">electronic</span> <span class="hlt">transport</span> properties of a quinone-based molecule sandwiched between two Au electrodes. The molecular switch can be reversibly switched between the reduced hydroquinone (HQ) and oxidized quinone (Q) states via redox reactions. The switching behavior of two forms is analyzed through their I- V curves, transmission spectra and molecular projected self-consistent Hamiltonian at zero bias. Then we discuss the transmission spectra of the HQ and Q forms at different bias, and explain the oscillation of current according to the transmission eigenstates of LUMO energy level for Q form. The results suggest that this kind of a quinone-based molecule is usable as one of the good candidates for redox-controlled molecular switches.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..MAR.F5008Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..MAR.F5008Q"><span><span class="hlt">Electronic</span> measurement of strain effects on spin <span class="hlt">transport</span> in silicon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qing, Lan; Tinkey, Holly; Appelbaum, Ian</p> <p></p> <p>Spin <span class="hlt">transport</span> in silicon is limited by the Elliott-Yafet spin relaxation mechanism, which is driven by scattering between degenerate conduction band valleys. Mechanical strain along a valley axis partially breaks this degeneracy, and will ultimately quench intervalley spin relaxation for transitions between states on orthogonal axes. Using a custom-designed and constructed strain probe, we study the effects of uniaxial compressive strain along the < 100 > direction on ballistic tunnel junction devices used to inject spin-polarized <span class="hlt">electrons</span> into silicon. The effects of strain-induced valley splitting will be presented and compared to our theoretical model. This work is supported by the Office of Naval Research under Contract No. N000141410317, the National Science Foundation under Contract No. ECCS-1231855, the Defense Threat Reduction Agency under Contract No. HDTRA1-13-1-0013, and the Maryland NanoCenter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhPro..75..948D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhPro..75..948D"><span>Relativistic Effects on <span class="hlt">Electron</span> <span class="hlt">Transport</span> in Magnetic Alloys</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Drchal, Václav; Kudrnovský, Josef; Turek, Ilja</p> <p></p> <p>We study the relativistic effects on <span class="hlt">electron</span> <span class="hlt">transport</span> in spin-polarized metals and random alloys on ab initio level using the fully relativistic tight-binding linear muffin-tin-orbital (TB-LMTO) method. We employ a Kubo linear-response approach adapted to disordered multisublattice systems in which the chemical disorder is described in terms of the coherent potential approximation (CPA). The CPA vertex corrections are included. We calculate both the Fermi surface and Fermi sea terms of the full conductivity tensor. We find that in cubic ferromagnetic 3d transition metals (Fe, Co, Ni) and their random binary alloys (Ni-Fe, Fe-Si) the Fermi sea term in the anomalous Hall conductivity is small in comparison with the Fermi surface term, however, in more complicated structures, such as hexagonal Co and selected Co-based Heusler alloys, it becomes important. We find an overall good agreement between the theory and experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26196817','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26196817"><span>Pauli-Heisenberg Oscillations in <span class="hlt">Electron</span> Quantum <span class="hlt">Transport</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Thibault, Karl; Gabelli, Julien; Lupien, Christian; Reulet, Bertrand</p> <p>2015-06-12</p> <p>We measure the current fluctuations emitted by a normal-metal-insulator-normal-metal tunnel junction with a very wide bandwidth, from 0.3 to 13 GHz, down to very low temperature T=35  mK. This allows us to perform the spectroscopy (i.e., measure the frequency dependence) of thermal noise (no dc bias, variable temperature) and shot noise (low temperature, variable dc voltage bias). Because of the very wide bandwidth of our measurement, we deduce the current-current correlator in the time domain. We observe the thermal decay of this correlator as well as its oscillations with a period h/eV, a direct consequence of the effect of the Pauli and Heisenberg principles in quantum <span class="hlt">electron</span> <span class="hlt">transport</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22492133','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22492133"><span>Conformation dependent <span class="hlt">electronic</span> <span class="hlt">transport</span> in a DNA double-helix</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kundu, Sourav Karmakar, S. N.</p> <p>2015-10-15</p> <p>We present a tight-binding study of conformation dependent <span class="hlt">electronic</span> <span class="hlt">transport</span> properties of DNA double-helix including its helical symmetry. We have studied the changes in the localization properties of DNA as we alter the number of stacked bases within every pitch of the double-helix keeping fixed the total number of nitrogen bases within the DNA molecule. We take three DNA sequences, two of them are periodic and one is random and observe that in all the cases localization length increases as we increase the radius of DNA double-helix i.e., number of nucleobases within a pitch. We have also investigated the effect of backbone energetic on the I-V response of the system and found that in presence of helical symmetry, depending on the interplay of conformal variation and disorder, DNA can be found in either metallic, semiconducting and insulating phases, as observed experimentally.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMMR13B..03S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMMR13B..03S"><span>Ab initio study of the <span class="hlt">electronic</span> <span class="hlt">transport</span> properties of silicates.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Soubiran, F.; Militzer, B.</p> <p>2016-12-01</p> <p>The Kepler spacecraft led to the discovery of numerous Super-Earths planets. Little is known about them, as there is no equivalent in the Solar System. It is uncertain whether they have a convective mantle like the Earth. It is also unclear if their mantle is insulating or conducting. In the latter case, for instance, the mantle could generate a magnetic field via dynamo processes. In order to better understand the properties of the silicates under pressure-temperature conditions relevant for the interiors of Super-Earth, we performed ab initio simulations based on density functional theory. We specifically explored the <span class="hlt">electronic</span> <span class="hlt">transport</span> properties, conductivity and reflectivity, to characterize their behavior in their different phases. We find that liquid and solid silicates behave differently and discuss consequences for the planetary interiors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1009202','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1009202"><span>Hot <span class="hlt">Electron</span> Generation and <span class="hlt">Transport</span> Using K(alpha) Emission</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Akli, K U; Stephens, R B; Key, M H; Bartal, T; Beg, F N; Chawla, S; Chen, C D; Fedosejevs, R; Freeman, R R; Friesen, H; Giraldez, E; Green, J S; Hey, D S; Higginson, D P; Hund, J; Jarrott, L C; Kemp, G E; King, J A; Kryger, A; Lancaster, K; LePape, S; Link, A; Ma, T; Mackinnon, A J; MacPhee, A G; McLean, H S; Murphy, C; Norreys, P A; Ovchinnikov, V; Patel, P K; Ping, Y; Sawada, H; Schumacher, D; Theobald, W; Tsui, Y Y; Van Woerkom, L D; Wei, M S; Westover, B; Yabuuchi, T</p> <p>2009-10-15</p> <p>We have conducted experiments on both the Vulcan and Titan laser facilities to study hot <span class="hlt">electron</span> generation and <span class="hlt">transport</span> in the context of fast ignition. Cu wires attached to Al cones were used to investigate the effect on coupling efficiency of plasma surround and the pre-formed plasma inside the cone. We found that with thin cones 15% of laser energy is coupled to the 40{micro}m diameter wire emulating a 40{micro}m fast ignition spot. Thick cone walls, simulating plasma in fast ignition, reduce coupling by x4. An increase of prepulse level inside the cone by a factor of 50 reduces coupling by a factor of 3.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ChPhB..25c7309H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ChPhB..25c7309H"><span>Velocity modulation of <span class="hlt">electron</span> <span class="hlt">transport</span> through a ferromagnetic silicene junction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huai-Hua, Shao; Dan, Guo; Ben-Liang, Zhou; Guang-Hui, Zhou</p> <p>2016-03-01</p> <p>We address velocity-modulation control of <span class="hlt">electron</span> wave propagation in a normal/ferromagnetic/normal silicene junction with local variation of Fermi velocity, where the properties of charge, valley, and spin <span class="hlt">transport</span> through the junction are investigated. By matching the wavefunctions at the normal-ferromagnetic interfaces, it is demonstrated that the variation of Fermi velocity in a small range can largely enhance the total conductance while keeping the current nearly fully valley- and spin-polarized. Further, the variation of Fermi velocity in ferromagnetic silicene has significant influence on the valley and spin polarization, especially in the low-energy regime. It may drastically reduce the high polarizations, which can be realized by adjusting the local application of a gate voltage and exchange field on the junction. Project supported by the National Natural Science Foundation of China (Grant No. 11274108).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JPhCS.244b2026A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JPhCS.244b2026A"><span>Hot <span class="hlt">electron</span> generation and <span class="hlt">transport</span> using Kα emission</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Akli, K. U.; Stephens, R. B.; Key, M. H.; Bartal, T.; Beg, F. N.; Chawla, S.; Chen, C. D.; Fedosejevs, R.; Freeman, R. R.; Friesen, H.; Giraldez, E.; Green, J. S.; Hey, D. S.; Higginson, D. P.; Hund, J.; Jarrott, L. C.; Kemp, G. E.; King, J. A.; Kryger, A.; Lancaster, K.; LePape, S.; Link, A.; Ma, T.; Mackinnon, A. J.; MacPhee, A. G.; McLean, H. S.; Murphy, C.; Norreys, P. A.; Ovchinnikov, V.; Patel, P. K.; Ping, Y.; Sawada, H.; Schumacher, D.; Theobald, W.; Tsui, Y. Y.; Van Woerkom, L. D.; Wei, M. S.; Westover, B.; Yabuuchi, T.</p> <p>2010-08-01</p> <p>We have conducted experiments on both the Vulcan and Titan laser facilities to study hot <span class="hlt">electron</span> generation and <span class="hlt">transport</span> in the context of fast ignition. Cu wires attached to Al cones were used to investigate the effect on coupling efficiency of plasma surround and the pre-formed plasma inside the cone. We found that with thin cones 15% of laser energy is coupled to the 40μm diameter wire emulating a 40μm fast ignition spot. Thick cone walls, simulating plasma in fast ignition, reduce coupling by x4. An increase of pre-pulse level inside the cone by a factor of 50 reduces coupling by a factor of 3.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..MARC26001B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..MARC26001B"><span><span class="hlt">Electron</span> <span class="hlt">Transport</span> Simulations of 4-Terminal Crossed Graphene Nanoribbons Devices</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brandimarte, Pedro; Papior, Nick R.; Engelund, Mads; Garcia-Lekue, Aran; Frederiksen, Thomas; Sánchez-Portal, Daniel</p> <p></p> <p>Recently, it has been reported theoretically a current switching mechanism by voltage control in a system made by two perpendicular 14-armchair graphene nanoribbons (GNRs). In order to investigate the possibilities of using crossed GNRs as ON/OFF devices, we have studied their <span class="hlt">electronic</span> and <span class="hlt">transport</span> properties as function structural parameters determining the crossing. Our calculations were performed with TranSIESTA code, which has been recently generalized to consider N >= 1 arbitrarily distributed electrodes at finite bias. We find that the transmission along each individual GNR and among them strongly depends on the stacking. For a 60° rotation angle, the lattice matching in the crossing region provokes a strong scattering effect that translates into an increased interlayer transmission. FP7 FET-ICT PAMS-project (European Commission, contract 610446), MINECO (Grant MAT2013-46593-C6-2-P) and Basque Dep. de Educación, UPV/EHU (Grant IT-756-13).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008PhDT.......107L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008PhDT.......107L"><span>Quantum chaos and <span class="hlt">electron</span> <span class="hlt">transport</span> properties in a quantum waveguide</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Hoshik</p> <p></p> <p>We numerically investigate <span class="hlt">electron</span> <span class="hlt">transport</span> properties in an <span class="hlt">electron</span> waveguide which can be constructed in 2DEG of the heterostructure of GaAs and AlGaAs. We apply R-matrix theory to solve a Schrodinger equation and construct a S-matrix, and we then calculate conductance of an <span class="hlt">electron</span> waveguide. We study single impurity scattering in a waveguide. A delta-function model as a single impurity is very attractive, but it has been known that delta-function potential does not give a convergent result in two or higher space dimensions. However, we find that it can be used as a single impurity in a waveguide with the truncation of the number of modes. We also compute conductance for a finite size impurity by using R-matrix theory. We propose an appropriate criteria for determining the cut-off mode for a delta-function impurity that reproduces the conductance of a waveguide when a finite impurity presents. We find quantum scattering echoes in a ripple waveguide. A ripple waveguide (or cavity) is widely used for quantum chaos studies because it is easy to control a particle's dynamics. Moreover we can obtain an exact expression of Hamiltonian matrix with for the waveguide using a simple coordinate transformation. Having an exact Hamiltonian matrix reduces computation time significantly. It saves a lot of computational needs. We identify three families of resonance which correspond to three different classical phase space structures. Quasi bound states of one of those resonances reside on a hetero-clinic tangle formed by unstable manifolds and stable manifolds in the phase space of a corresponding classical system. Resonances due to these states appear in the conductance in a nearly periodic manner as a function of energy. Period from energy frequency gives a good agreement with a prediction of the classical theory. We also demonstrate wavepacket dynamics in a ripple waveguide. We find quantum echoes in the transmitted probability of a wavepacket. The period of echoes also</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20497376','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20497376"><span>Physiological links among alternative <span class="hlt">electron</span> <span class="hlt">transport</span> pathways that reduce and oxidize plastoquinone in Arabidopsis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Okegawa, Yuki; Kobayashi, Yoshichika; Shikanai, Toshiharu</p> <p>2010-08-01</p> <p>In addition to linear <span class="hlt">electron</span> <span class="hlt">transport</span> from water to NADP(+) , alternative <span class="hlt">electron</span> <span class="hlt">transport</span> pathways are believed to regulate photosynthesis. In the two routes of photosystem I (PSI) cyclic <span class="hlt">electron</span> <span class="hlt">transport</span>, <span class="hlt">electrons</span> are recycled from the stromal reducing pool to plastoquinone (PQ), generating additional ΔpH (proton gradient across thylakoid membranes). Plastid terminal oxidase (PTOX) accepts <span class="hlt">electrons</span> from PQ and transfers them to oxygen to produce water. Although both <span class="hlt">electron</span> <span class="hlt">transport</span> pathways share the PQ pool, it is unclear whether they interact in vivo. To investigate the physiological link between PSI cyclic <span class="hlt">electron</span> <span class="hlt">transport</span>-dependent PQ reduction and PTOX-dependent PQ oxidation, we characterized mutants defective in both functions. Impairment of PSI cyclic <span class="hlt">electron</span> <span class="hlt">transport</span> suppressed leaf variegation in the Arabidopsis immutans (im) mutant, which is defective in PTOX. The im variegation was more effectively suppressed in the pgr5 mutant, which is defective in the main pathway of PSI cyclic <span class="hlt">electron</span> <span class="hlt">transport</span>, than in the crr2-2 mutant, which is defective in the minor pathway. In contrast to this chloroplast development phenotype, the im defect alleviated the growth phenotype of the crr2-2 pgr5 double mutant. This was accompanied by partial suppression of stromal over-reduction and restricted linear <span class="hlt">electron</span> <span class="hlt">transport</span>. We discuss the function of the alternative <span class="hlt">electron</span> <span class="hlt">transport</span> pathways in both chloroplast development and photosynthesis in mature leaves. © 2010 The Authors. Journal compilation © 2010 Blackwell Publishing Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009PhDT.......167B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009PhDT.......167B"><span>Characterization of ionic <span class="hlt">transport</span> in polymer and <span class="hlt">electronic</span> <span class="hlt">transport</span> in disordered selenium and ceramic materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bandyopadhyay, Subhasish</p> <p></p> <p>In this thesis, the properties of <span class="hlt">electronic</span> conduction in vanadium (donor) and scandium (acceptor) doped Ba0.7Sr0.3TiO3 ceramics, amorphous Selenium and ionic conduction in polyester polyol based polyurethane have been investigated. The leakage current of bulk vanadium (donor) and scandium (acceptor) doped Ba0.7Sr0.3TiO3 ceramics structures measured using gold electrical contacts have been characterized and analyzed. Vanadium doping reduces the ohmic leakage current that dominates the <span class="hlt">transport</span> characteristics up to 5 kV/cm. The Arrhenius activation energy is 0.18, 0.20 and 0.23 eV for 1, 2 and 4 at % V-doped samples, respectively. Above this field, the current-voltage characteristics exhibit discontinuous current transitions associated with trap filling by <span class="hlt">electronic</span> carriers. At higher fields, trap controlled space charge limited conduction (SCLC) is observed with an effective mobility of 4+/-1x10-7 cm2/V s, characteristic of <span class="hlt">electronic</span> <span class="hlt">transport</span> process that involves quasi equilibrium between conduction in the band and trapping. In contrast, the leakage current of Sc-doped samples increases with impurity concentration and exhibits a 0.60 eV activation energy. In this case, the limiting current conduction mechanism is the <span class="hlt">transport</span> of holes over the electrostatic barrier at grain boundaries. Comparison of these results to those on similarly-doped homoepitaxial SrTiO3 thin-films deposited on single-crystal and bicrystal substrates helped to identify the characteristics of <span class="hlt">transport</span> in the bulk and across grain boundaries for this class of materials. Electrical, thermal and Li <span class="hlt">transport</span> properties have been measured for polyester polyol and isocyanate-based polyurethanes doped with Lithium trifluoromethanesulfonimide (LiTFSI) and Lithium perchlorate (LiClO4) Electrical conductivities are estimated at 10-5--10-6 S/cm near 300 K. The conductivities show Vogel-Tammann-Fulcher (VTF) behavior over a wide temperature ranges. Differential scanning calorimetry (DSC) shows</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986PhRvB..34.2158K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986PhRvB..34.2158K"><span><span class="hlt">Transport</span> of <span class="hlt">electron</span>-hole plasma in germanium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kirch, S. J.; Wolfe, J. P.</p> <p>1986-08-01</p> <p>Time-resolved luminescence imaging techniques are used to observe the spectral and spatial evolution of laser-generated <span class="hlt">electron</span>-hole plasma in Ge. Both pulsed and cw excitation conditions are examined above and below the critical temperature for <span class="hlt">electron</span>-hole liquid formation, Tc(LG). For Q-switched Nd-doped yttrium aluminum garnet laser excitation, the <span class="hlt">transport</span> behavior is qualitatively similar above and below Tc(LG), although the luminescence spectrum undergoes significant changes in this temperature range. A rapid initial expansion (v~105 cm/s) is followed by a period of slower growth which gradually reduces as the carriers recombine. The initial velocity for pulsed excitation increases monotonically as the crystal temperature is lowered and saturates near the phonon sound velocity for high-energy excitation. These observations are consistent with phonon-wind driven <span class="hlt">transport</span>. For intense Q-switched excitation, the motion is characterized by three regimes: (1) During the laser pulse the plasma expands as a large drop with near-unity filling fraction. (2) Expansion at near-sonic velocity continues after the peak of the laser pulse due to a ``prompt'' pulse of ballistic phonons produced by the carrier thermalization process. (3) After this intense phonon wind passes the carrier distribution, the expansion velocity abruptly decreases, but the plasma continues to expand more slowly under the influence of a ``hot spot'' produced at the excitation point. The sound barrier observed on these time scales (>=30 ns) can be explained in terms of nonlinear damping of the plasma motion near the sound velocity. For cw excitation, the expansion is observed to occur at much lower velocities (v~104 cm/s). These expansion rates are much too low to require the inclusion of a drifted Fermi distribution in the spectral analysis as has been previously suggested. Instead, based upon a careful study of corresponding spectral data, an alternative explanation for these spectra is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22493896','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22493896"><span><span class="hlt">Electron</span> <span class="hlt">transport</span> in molecular junctions with graphene as protecting layer</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hüser, Falco; Solomon, Gemma C.</p> <p>2015-12-07</p> <p>We present ab initio <span class="hlt">transport</span> calculations for molecular junctions that include graphene as a protecting layer between a single molecule and gold electrodes. This vertical setup has recently gained significant interest in experiment for the design of particularly stable and reproducible devices. We observe that the signals from the molecule in the <span class="hlt">electronic</span> transmission are overlayed by the signatures of the graphene sheet, thus raising the need for a reinterpretation of the transmission. On the other hand, we see that our results are stable with respect to various defects in the graphene. For weakly physiosorbed molecules, no signs of interaction with the graphene are evident, so the <span class="hlt">transport</span> properties are determined by offresonant tunnelling between the gold leads across an extended structure that includes the molecule itself and the additional graphene layer. Compared with pure gold electrodes, calculated conductances are about one order of magnitude lower due to the increased tunnelling distance. Relative differences upon changing the end group and the length of the molecule on the other hand, are similar.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..MART19012K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..MART19012K"><span>Anomalous <span class="hlt">electron</span> <span class="hlt">transport</span> in ferromagnetic MnBi films</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kharel, Parashu; Sellmyer, D. J.</p> <p>2011-03-01</p> <p>Materials having high spin polarization, large perpendicular magnetic anisotropy and high Curie temperature hold great potential for a range of spintronic applications. MnBi has the hexagonal NiAs structure and possesses strong permanent magnet and magneto-optical properties. Our recent research shows that MnBi exhibits a high <span class="hlt">transport</span> spin polarization of 63%, so it is useful to investigate the <span class="hlt">electron</span> <span class="hlt">transport</span> properties of this material. We have found that MnBi is a metallic conductor but the resistivity shows an anomalous temperature dependence at low temperature. Analysis of the Hall data for various samples shows that the extraordinary Hall effect is the dominant part in the transverse Hall effect and a Hall angle of 2.8% has been measured. An experimental investigation on the origin of the observed large extraordinary Hall effect in MnBi thin films will be discussed. This research is supported by NSF-MRSEC Grant DMR-0820521, the DOE Grant DE-FG02-04ER46152 and NCMN. S. Mangin, D. Ravelosona, J. A. Katine, M. J. Carey, B. D. Terris and Eric E. Fullerton, Nature Mater. 5, 210 (2006).</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008APS..MARQ24013S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008APS..MARQ24013S"><span><span class="hlt">Electron</span> <span class="hlt">Transport</span> through Models for Small-World Nanomaterials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Solomon, Lazarus; Novotny, Mark</p> <p>2008-03-01</p> <p>We investigate the quantum <span class="hlt">transport</span> of (spinless) <span class="hlt">electrons</span> through simplified models related to small-world nanomaterials. We employ a tight-binding Hamiltonian, and obtain the transmission coefficient from a matrix solution of the associated time-independent Schrödinger Equation. The system studied corresponds to d=1 semi-infinite input and output leads, connected to a `blob' of N atoms. We first present exact results for N inter-connected atoms, a fully-connected graph. The exact solution, for any N, is given both for symmetric and non-symmetric connections between the `blob' and the input/output. We then present numerical results obtained by removing some of the connections within the N-site `blob', thereby approaching <span class="hlt">transport</span> through a small-world nanomaterial [1-4]. [1] S. Caliskan, M.A. Novotny, and J.I. Cerd'a, J. Appl. Phys., 102, 013707 (2007). [2] M.A. Novotny et al., J. Appl. Phys., 97, 10B309 (2005). [3] M.A. Novotny and S.M. Wheeler, Braz. J. Physics 34, 395 (2004). [4] J. Yancey, M.A. Novotny, and S.R. Gwaltney, 2008 March Meeting presentation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20090014179&hterms=DSP&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DDSP','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20090014179&hterms=DSP&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DDSP"><span>Re-Configurable <span class="hlt">Electronics</span> Characterization under Extreme Thermal <span class="hlt">Environment</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stoica, Adrian; Lacayo, Veronica; Ramesham, Rajeshuni; Keymeulen, Didier; Zebulum, Ricardo; Neff, Joe; Burke, Gary; Daud, Taher</p> <p>2005-01-01</p> <p>The need for reconfigurable <span class="hlt">electronics</span> is driven by requirements to survive longer missions and harsher <span class="hlt">environments</span>. It is possible to compensate for degradations in Extreme <span class="hlt">Environments</span> (EE). EE has effect on <span class="hlt">electronics</span>: circuits are designed to exploit device characteristics and when a certain temperature or radiation range is exceeded the circuit function gradually degrades. It is possible to employ Hardening by reconfiguration (HBR) to mitigate drifts, degradation, or damage on <span class="hlt">electronic</span> devices in EE by using reconfigurable devices and an adaptive self-reconfiguration of circuit topology. In this manner degraded components can be salvaged, and completely damaged components can be bypassed. The challenge of conventional design is replaced with that of designing a recover process that automatically performs the (re) design in place of the designer. The objective of testing a Digital Signal Processor (DSP) under the extreme temperatures was to determine the lowest temperature at which the DAP can operate. The objective of testing a Xilinx VirtexII Pro FPGA board was to initially find our whether the evaluation board and the FPGA would survive and continue at temperature ranges from -180 C, and 120 C. The Virtex II functioned correctly at the temperatures tested. The next test was done on the GM-C filter building block using the same temperature range as the Virtex II. The current lower and upper limits were shown to be reduced as the temperature gets lower. The device function can be recovered by increasing the Vb from .08V to .85V. The negative and positive saturation voltages increases as the temperature gets higher. The function of the device can be recovered by decreasing the Vb from .8V to around .75V. The next test was performed to test the recovery of the GmC low pass filter through Vb in a filter circuit. The test indicate that bias voltage control adjustment is an efficient mechanism for circuit recovery at extreme temperatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20090014179&hterms=neff&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dneff','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20090014179&hterms=neff&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dneff"><span>Re-Configurable <span class="hlt">Electronics</span> Characterization under Extreme Thermal <span class="hlt">Environment</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stoica, Adrian; Lacayo, Veronica; Ramesham, Rajeshuni; Keymeulen, Didier; Zebulum, Ricardo; Neff, Joe; Burke, Gary; Daud, Taher</p> <p>2005-01-01</p> <p>The need for reconfigurable <span class="hlt">electronics</span> is driven by requirements to survive longer missions and harsher <span class="hlt">environments</span>. It is possible to compensate for degradations in Extreme <span class="hlt">Environments</span> (EE). EE has effect on <span class="hlt">electronics</span>: circuits are designed to exploit device characteristics and when a certain temperature or radiation range is exceeded the circuit function gradually degrades. It is possible to employ Hardening by reconfiguration (HBR) to mitigate drifts, degradation, or damage on <span class="hlt">electronic</span> devices in EE by using reconfigurable devices and an adaptive self-reconfiguration of circuit topology. In this manner degraded components can be salvaged, and completely damaged components can be bypassed. The challenge of conventional design is replaced with that of designing a recover process that automatically performs the (re) design in place of the designer. The objective of testing a Digital Signal Processor (DSP) under the extreme temperatures was to determine the lowest temperature at which the DAP can operate. The objective of testing a Xilinx VirtexII Pro FPGA board was to initially find our whether the evaluation board and the FPGA would survive and continue at temperature ranges from -180 C, and 120 C. The Virtex II functioned correctly at the temperatures tested. The next test was done on the GM-C filter building block using the same temperature range as the Virtex II. The current lower and upper limits were shown to be reduced as the temperature gets lower. The device function can be recovered by increasing the Vb from .08V to .85V. The negative and positive saturation voltages increases as the temperature gets higher. The function of the device can be recovered by decreasing the Vb from .8V to around .75V. The next test was performed to test the recovery of the GmC low pass filter through Vb in a filter circuit. The test indicate that bias voltage control adjustment is an efficient mechanism for circuit recovery at extreme temperatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1238384','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1238384"><span>Radiation Hardened <span class="hlt">Electronics</span> Destined For Severe Nuclear Reactor <span class="hlt">Environments</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Holbert, Keith E.; Clark, Lawrence T.</p> <p>2016-02-19</p> <p>Post nuclear accident conditions represent a harsh <span class="hlt">environment</span> for <span class="hlt">electronics</span>. The full station blackout experience at Fukushima shows the necessity for emergency sensing capabilities in a radiation-enhanced <span class="hlt">environment</span>. This NEET (Nuclear Energy Enabling Technologies) research project developed radiation hardened by design (RHBD) <span class="hlt">electronics</span> using commercially available technology that employs commercial off-the-shelf (COTS) devices and present generation circuit fabrication techniques to improve the total ionizing dose (TID) hardness of <span class="hlt">electronics</span>. Such technology not only has applicability to severe accident conditions but also to facilities throughout the nuclear fuel cycle in which radiation tolerance is required. For example, with TID tolerance to megarads of dose, <span class="hlt">electronics</span> could be deployed for long-term monitoring, inspection and decontamination missions. The present work has taken a two-pronged approach, specifically, development of both board and application-specific integrated circuit (ASIC) level RHBD techniques. The former path has focused on TID testing of representative microcontroller ICs with embedded flash (eFlash) memory, as well as standalone flash devices that utilize the same fabrication technologies. The standalone flash devices are less complicated, allowing better understanding of the TID response of the crucial circuits. Our TID experiments utilize biased components that are in-situ tested, and in full operation during irradiation. A potential pitfall in the qualification of memory circuits is the lack of rigorous testing of the possible memory states. For this reason, we employ test patterns that include all ones, all zeros, a checkerboard of zeros and ones, an inverse checkerboard, and random data. With experimental evidence of improved radiation response for unbiased versus biased conditions, a demonstration-level board using the COTS devices was constructed. Through a combination of redundancy and power gating, the demonstration</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12322742','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12322742"><span>Organic nature of colloidal actinides <span class="hlt">transported</span> in surface water <span class="hlt">environments</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Santschi, Peter H; Roberts, Kimberly A; Guo, Laodong</p> <p>2002-09-01</p> <p>Elevated levels of (239,240)Pu and 241Am have been present in surficial soils of the Rocky Flats Environmental Technology Site (RFETS), CO, since the 1960s, when soils were locally contaminated in the 1960s by leaking drums stored on the 903 Pad. Further dispersion of contaminated soil particles was by wind and water. From 1998 until 2001, we examined actinide ((239,240)Pu and 241Am) concentrations and phase speciation in the surface <span class="hlt">environment</span> at RFETS through field studies and laboratory experiments. Measurements of total (239,240)Pu and 241Am concentrations in storm runoff and pond discharge samples, collected during spring and summer times in 1998-2000, demonstrate that most of the (239,240)Pu and 241Am <span class="hlt">transported</span> from contaminated soils to streams occurred in the particulate (> or = 0.45 microm; 40-90%) and colloidal (approximately 2 nm or 3 kDa to 0.45 microm; 10-60%) phases. Controlled laboratory investigations of soil resuspension, which simulated storm and erosion events, confirmed that most of the Pu in the 0.45 microm filter-passing phase was in the colloidal phase (> or = 80%) and that remobilization of colloid-bound Pu during soil erosion events can be greatly enhanced by humic and fulvic acids present in these soils. Most importantly, isoelectric focusing experiments of radiolabeled colloidal matter extracted from RFETS soils revealed that colloidal Pu is in the four-valent state and is mostly associated with a negatively charged organic macromolecule with a pH(IEP) of 3.1 and a molecular weight of 10-15 kDa, rather than with the more abundant inorganic (iron oxide and clay) colloids. This finding has important ramifications for possible remediation, erosion controls, and land-management strategies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005JaJAP..44..523L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005JaJAP..44..523L"><span>Intrinsic <span class="hlt">Electronic</span> <span class="hlt">Transport</span> through Alkanedithiol Self-Assembled Monolayer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Takhee; Wang, Wenyong; Reed, Mark A.</p> <p>2005-01-01</p> <p><span class="hlt">Electronic</span> <span class="hlt">transport</span> through an alkanedithiol self-assembled monolayer (SAM) is investigated using a nanometer scale device. Temperature-independent current-voltage characteristics are observed, indicating tunneling is the main conduction mechanism. The measured current-voltage characteristics are analyzed with a metal-insulator-metal tunneling model. The inelastic <span class="hlt">electron</span> tunneling spectroscopy (IETS) study on the octanedithiol device clearly shows the vibrational signatures of molecules. The pronounced IETS peaks correspond to vibrational modes perpendicular to the junction interface, which include the stretching modes of Au-S (at 33 mV) and C-C (at 133 mV), and wagging mode of CH2 (at 158 mV). Intrinsic linewidths are determined as 1.69 (upper limit), 3.73± 0.98, and 13.5± 2.4 meV for Au-S, C-C streching modes, and CH2 wagging mode, respectively. The observed peak intensities and peak widths are in good agreement with theoretical predictions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1178203','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1178203"><span>Fast <span class="hlt">electron</span> <span class="hlt">transport</span> in lower-hybrid current drive</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kupfer, K.; Bers, A.</p> <p>1991-01-01</p> <p>We generalize the quasilinear-Fokker-Planck formulation for lower-hybrid current drive to include the wave induced radial <span class="hlt">transport</span> of fast <span class="hlt">electrons</span>. Toroidal ray tracing shows that the wave fields in the plasma develop a large poloidal component associated with the upshift in k1l and the filling of the "spectral gap". These fields lead to an enhanced radial E x B drift of resonant <span class="hlt">electrons</span>. Two types of radial flows are obtained: an outward convective flow driven by the asymmetry in the poloidal wave spectrum, and a diffusive flow proportional to the width of the poloidal spectrum. Simulations of Alcator C and JT60, show that the radial convection velocity has a broad maximum of nearly 1 m/sec and is independent of the amplitude of fields. In both cases, the radial diffusion is found to be highly localized near the magnetic axis. For JT60, the peak of the diffusion profile can be quite large, nearly 1 m2/sec.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JChPh.146d4110M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JChPh.146d4110M"><span><span class="hlt">Electron</span> <span class="hlt">transport</span> in real time from first-principles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Morzan, Uriel N.; Ramírez, Francisco F.; González Lebrero, Mariano C.; Scherlis, Damián A.</p> <p>2017-01-01</p> <p>While the vast majority of calculations reported on molecular conductance have been based on the static non-equilibrium Green's function formalism combined with density functional theory (DFT), in recent years a few time-dependent approaches to <span class="hlt">transport</span> have started to emerge. Among these, the driven Liouville-von Neumann equation [C. G. Sánchez et al., J. Chem. Phys. 124, 214708 (2006)] is a simple and appealing route relying on a tunable rate parameter, which has been explored in the context of semi-empirical methods. In the present study, we adapt this formulation to a density functional theory framework and analyze its performance. In particular, it is implemented in an efficient all-<span class="hlt">electron</span> DFT code with Gaussian basis functions, suitable for quantum-dynamics simulations of large molecular systems. At variance with the case of the tight-binding calculations reported in the literature, we find that now the initial perturbation to drive the system out of equilibrium plays a fundamental role in the stability of the <span class="hlt">electron</span> dynamics. The equation of motion used in previous tight-binding implementations with massive electrodes has to be modified to produce a stable and unidirectional current during time propagation in time-dependent DFT simulations using much smaller leads. Moreover, we propose a procedure to get rid of the dependence of the current-voltage curves on the rate parameter. This method is employed to obtain the current-voltage characteristic of saturated and unsaturated hydrocarbons of different lengths, with very promising prospects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14507427','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14507427"><span>Endosymbiosis and the design of eukaryotic <span class="hlt">electron</span> <span class="hlt">transport</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Berry, Stephan</p> <p>2003-09-30</p> <p>The bioenergetic organelles of eukaryotic cells, mitochondria and chloroplasts, are derived from endosymbiotic bacteria. Their <span class="hlt">electron</span> <span class="hlt">transport</span> chains (ETCs) resemble those of free-living bacteria, but were tailored for energy transformation within the host cell. Parallel evolutionary processes in mitochondria and chloroplasts include reductive as well as expansive events: On one hand, bacterial complexes were lost in eukaryotes with a concomitant loss of metabolic flexibility. On the other hand, new subunits have been added to the remaining bacterial complexes, new complexes have been introduced, and elaborate folding patterns of the thylakoid and mitochondrial inner membranes have emerged. Some bacterial pathways were reinvented independently by eukaryotes, such as parallel routes for quinol oxidation or the use of various anaerobic <span class="hlt">electron</span> acceptors. Multicellular organization and ontogenetic cycles in eukaryotes gave rise to further modifications of the bioenergetic organelles. Besides mitochondria and chloroplasts, eukaryotes have ETCs in other membranes, such as the plasma membrane (PM) redox system, or the cytochrome P450 (CYP) system. These systems have fewer complexes and simpler branching patterns than those in energy-transforming organelles, and they are often adapted to non-bioenergetic functions such as detoxification or cellular defense.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Nanot..26o5102B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Nanot..26o5102B"><span>Nanoscale <span class="hlt">electron</span> <span class="hlt">transport</span> measurements of immobilized cytochrome P450 proteins</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bostick, Christopher D.; Flora, Darcy R.; Gannett, Peter M.; Tracy, Timothy S.; Lederman, David</p> <p>2015-04-01</p> <p>Gold nanopillars, functionalized with an organic self-assembled monolayer, can be used to measure the electrical conductance properties of immobilized proteins without aggregation. Measurements of the conductance of nanopillars with cytochrome P450 2C9 (CYP2C9) proteins using conducting probe atomic force microscopy demonstrate that a correlation exists between the energy barrier height between hopping sites and CYP2C9 metabolic activity. Measurements performed as a function of tip force indicate that, when subjected to a large force, the protein is more stable in the presence of a substrate. This agrees with the hypothesis that substrate entry into the active site helps to stabilize the enzyme. The relative distance between hopping sites also increases with increasing force, possibly because protein functional groups responsible for <span class="hlt">electron</span> <span class="hlt">transport</span> (ETp) depend on the structure of the protein. The inhibitor sulfaphenazole, in addition to the previously studied aniline, increased the barrier height for <span class="hlt">electron</span> transfer and thereby makes CYP2C9 reduction more difficult and inhibits metabolism. This suggests that P450 Type II binders may decrease the ease of ETp processes in the enzyme, in addition to occupying the active site.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006APS..MAR.Q1112B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006APS..MAR.Q1112B"><span>Phonon engineering of <span class="hlt">electronic</span> <span class="hlt">transport</span> in hybrid nanotubes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Balandin, Alexander A.; Fonoberov, Vladimir A.</p> <p>2006-03-01</p> <p>Recently, a number of biological nanoscale objects, including tobacco mosaic viruses (TMV), have been employed as templates for assembly of inorganic nanostructures. This approach can potentially lead to a new method of fabrication of nanoelectronic circuits beyond conventional CMOS. Here we theoretically demonstrate that in addition to their role as nano-templates [1], the elastically soft TMVs can improve <span class="hlt">electron</span> <span class="hlt">transport</span> in the nanotubes grown on them [2]. In the simulated hybrid nanostructures, which consist of silicon or silica nanotubes on TMVs, the confined acoustic phonons are found to be redistributed between the nanotube shell and the acoustically soft virus enclosure. As a result, the low-temperature <span class="hlt">electron</span> mobility in the hybrid TMV-silicon nanotube can increase up to a factor of four compared to that of an empty silicon nanotube [2]. Our estimates also indicate an enhancement of the low-temperature thermal conductivity in the TMV-silicon nanotube, which can lead to improvements in heat removal from the hybrid nanostructure-based circuits. The authors acknowledge the support of MARCO and its Functional Engineered Nano Architectonics (FENA) Focus Center. [1] W.L. Liu, K. Alim, A.A. Balandin et al., Appl. Phys. Lett. 86, 253108 (2005); [2] V.A. Fonoberov and A.A. Balandin, Nano Lett. 5, 1920 (2005).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28147541','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28147541"><span><span class="hlt">Electron</span> <span class="hlt">transport</span> in real time from first-principles.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Morzan, Uriel N; Ramírez, Francisco F; González Lebrero, Mariano C; Scherlis, Damián A</p> <p>2017-01-28</p> <p>While the vast majority of calculations reported on molecular conductance have been based on the static non-equilibrium Green's function formalism combined with density functional theory (DFT), in recent years a few time-dependent approaches to <span class="hlt">transport</span> have started to emerge. Among these, the driven Liouville-von Neumann equation [C. G. Sánchez et al., J. Chem. Phys. 124, 214708 (2006)] is a simple and appealing route relying on a tunable rate parameter, which has been explored in the context of semi-empirical methods. In the present study, we adapt this formulation to a density functional theory framework and analyze its performance. In particular, it is implemented in an efficient all-<span class="hlt">electron</span> DFT code with Gaussian basis functions, suitable for quantum-dynamics simulations of large molecular systems. At variance with the case of the tight-binding calculations reported in the literature, we find that now the initial perturbation to drive the system out of equilibrium plays a fundamental role in the stability of the <span class="hlt">electron</span> dynamics. The equation of motion used in previous tight-binding implementations with massive electrodes has to be modified to produce a stable and unidirectional current during time propagation in time-dependent DFT simulations using much smaller leads. Moreover, we propose a procedure to get rid of the dependence of the current-voltage curves on the rate parameter. This method is employed to obtain the current-voltage characteristic of saturated and unsaturated hydrocarbons of different lengths, with very promising prospects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhD...50a5205Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhD...50a5205Z"><span>Cross-field <span class="hlt">transport</span> of <span class="hlt">electrons</span> at the magnetic throat in an annular plasma reactor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Yunchao; Charles, Christine; Boswell, Rod</p> <p>2017-01-01</p> <p>Cross-field <span class="hlt">transport</span> of <span class="hlt">electrons</span> has been studied at the magnetic throat of the annular Chi-Kung reactor. This annular configuration allows the creation of a low pressure argon plasma with two distinct <span class="hlt">electron</span> heating locations by independently operating a radio-frequency antenna surrounding the outer source tube, or an antenna housed inside the inner source tube. The two antenna cases show opposite variation trends in radial profiles of <span class="hlt">electron</span> energy probability function, <span class="hlt">electron</span> density, plasma potential and <span class="hlt">electron</span> temperature. The momentum and energy <span class="hlt">transport</span> coefficients are obtained from the <span class="hlt">electron</span> energy probability functions, and the related <span class="hlt">electron</span> fluxes follow the path of <span class="hlt">electron</span> cooling across the magnetic throat.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26512795','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26512795"><span>Detailed Monte Carlo Simulation of <span class="hlt">electron</span> <span class="hlt">transport</span> and <span class="hlt">electron</span> energy loss spectra.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Attarian Shandiz, M; Salvat, F; Gauvin, R</p> <p>2016-11-01</p> <p>A computer program for detailed Monte Carlo simulation of the <span class="hlt">transport</span> of <span class="hlt">electrons</span> with kinetic energies in the range between about 0.1 and about 500 keV in bulk materials and in thin solid films is presented. Elastic scattering is described from differential cross sections calculated by the relativistic (Dirac) partial-wave expansion method with different models of the scattering potential. Inelastic interactions are simulated from an optical-data model based on an empirical optical oscillator strength that combines optical functions of the solid with atomic photoelectric data. The generalized oscillator strength is built from the adopted optical oscillator strength by using an extension algorithm derived from Lindhard's dielectric function for a free-<span class="hlt">electron</span> gas. It is shown that simulated backscattering fractions of <span class="hlt">electron</span> beams from bulk (semi-infinite) specimens are in good agreement with experimental data for beam energies from 0.1 keV up to about 100 keV. Simulations also yield transmitted and backscattered fractions of <span class="hlt">electron</span> beams on thin solid films that agree closely with measurements for different film thicknesses and incidence angles. Simulated most probable deflection angles and depth-dose distributions also agree satisfactorily with measurements. Finally, <span class="hlt">electron</span> energy loss spectra of several elemental solids are simulated and the effects of the beam energy and the foil thickness on the signal to background and signal to noise ratios are investigated. SCANNING 38:475-491, 2016. © 2015 Wiley Periodicals, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010PhDT........75K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010PhDT........75K"><span>Atomistic modeling of <span class="hlt">electronic</span> structure and <span class="hlt">transport</span> in disordered nanostructures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kharche, Neerav</p> <p></p> <p>As the Si-CMOS technology approaches the end of the International Technology Roadmap for Semiconductors (ITRS), the semiconductor industry faces a formidable challenge to continue the transistor scaling according to Moore's law. To continue the scaling of classical devices, alternative channel materials such as SiGe, carbon nanotubes, nanowires, and III-V based materials are being investigated along with novel 3D device geometries. Researchers are also investigating radically new quantum computing devices, which are expected to perform calculations faster than the existing classical Si-CMOS based structures. Atomic scale disorders such as interface roughness, alloy randomness, non-uniform strain, and dopant fluctuations are routinely present in the experimental realization of such devices. These disorders now play an increasingly important role in determining the <span class="hlt">electronic</span> structure and <span class="hlt">transport</span> properties as device sizes enter the nanometer regime. This work employs the atomistic tight-binding technique, which is ideally suited for modeling systems with local disorders on an atomic scale. High-precision multi-million atom <span class="hlt">electronic</span> structure calculations of (111) Si surface quantum wells and (100) SiGe/Si/SiGe heterostructure quantum wells are performed to investigate the modulation of valley splitting induced by atomic scale disorders. The calculations presented here resolve the existing discrepancies between theoretically predicted and experimentally measured valley splitting, which is an important design parameter in quantum computing devices. Supercell calculations and the zone-unfolding method are used to compute the bandstructures of inhomogeneous nanowires made of AlGaAs and SiGe and their connection with the transmission coefficients computed using non-equilibrium Green's function method is established. A unified picture of alloy nanowires emerges, in which the nanodevice (transmission) and nanomaterials (bandstructure) viewpoints complement each other</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..MARY16008C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..MARY16008C"><span>Single and Few Layer Silicene: Structural, <span class="hlt">Electronic</span> and <span class="hlt">Transport</span> Properties</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carey, J. David; Roome, Nathanael</p> <p></p> <p>Single layer silicene has weaker π bonding that graphene resulting in buckling of the Si atoms in different sub-lattices. Despite the loss of planarity, a linear bandstructure emerges where we find a Fermi velocity of about 5.3 x 105 m/s. Determination of the phonon dispersion characteristics reveals a Γ point optical phonon with an energy of 69 meV and a K point optical phonon with an energy of 62 meV. In graphene these phonons play important role in scattering <span class="hlt">electrons</span>, and in Raman spectroscopy, but have larger energies of 194 and 166 meV, respectively. The lower phonon energies in silicene, arising from the higher atomic masses, would be expected to scatter carriers efficiently and limit carrier mobility. We have calculated, however, that the <span class="hlt">electron</span>-optical phonon coupling matrix elements are about a factor of 25 times smaller than in graphene and this important result will help with the further development of silicene based devices due to reduced phonon scattering. The two stable stacking configurations of bilayer silicene, AA and AB, now have to account of the position of the atomic buckling in the two layers, leading to four possible atomic configurations with the buckling between the layers being in- or out-of-phase with each other. We find that in contrast to graphene, the two stable configurations are based on AA type stacking being about 70 meV per atom more stable than AB stacking. The potential for elemental layered materials beyond graphene for device applications will also be discussed. Single and Few Layer Silicene: Structural, <span class="hlt">Electronic</span> and <span class="hlt">Transport</span> Properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PlPhR..42..713G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PlPhR..42..713G"><span>Simulation of <span class="hlt">electron</span> beam formation and <span class="hlt">transport</span> in a gas-filled <span class="hlt">electron</span>-optical system with a plasma emitter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grishkov, A. A.; Kornilov, S. Yu.; Rempe, N. G.; Shidlovskiy, S. V.; Shklyaev, V. A.</p> <p>2016-07-01</p> <p>The results of computer simulations of the <span class="hlt">electron</span>-optical system of an <span class="hlt">electron</span> gun with a plasma emitter are presented. The simulations are performed using the KOBRA3-INP, XOOPIC, and ANSYS codes. The results describe the <span class="hlt">electron</span> beam formation and <span class="hlt">transport</span>. The <span class="hlt">electron</span> trajectories are analyzed. The mechanisms of gas influence on the energy inhomogeneity of the beam and its current in the regions of beam primary formation, acceleration, and <span class="hlt">transport</span> are described. Recommendations for optimizing the <span class="hlt">electron</span>-optical system with a plasma emitter are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22614102','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22614102"><span>Simulation of <span class="hlt">electron</span> beam formation and <span class="hlt">transport</span> in a gas-filled <span class="hlt">electron</span>-optical system with a plasma emitter</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Grishkov, A. A.; Kornilov, S. Yu. Rempe, N. G.; Shidlovskiy, S. V.; Shklyaev, V. A.</p> <p>2016-07-15</p> <p>The results of computer simulations of the <span class="hlt">electron</span>-optical system of an <span class="hlt">electron</span> gun with a plasma emitter are presented. The simulations are performed using the KOBRA3-INP, XOOPIC, and ANSYS codes. The results describe the <span class="hlt">electron</span> beam formation and <span class="hlt">transport</span>. The <span class="hlt">electron</span> trajectories are analyzed. The mechanisms of gas influence on the energy inhomogeneity of the beam and its current in the regions of beam primary formation, acceleration, and <span class="hlt">transport</span> are described. Recommendations for optimizing the <span class="hlt">electron</span>-optical system with a plasma emitter are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApPhL.109o2904O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApPhL.109o2904O"><span><span class="hlt">Electron</span> <span class="hlt">transport</span> and dielectric breakdown in silicon nitride using a charge <span class="hlt">transport</span> model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ogden, Sean P.; Lu, Toh-Ming; Plawsky, Joel L.</p> <p>2016-10-01</p> <p>Silicon nitride is an important material used in the <span class="hlt">electronics</span> industry. As such, the <span class="hlt">electronic</span> <span class="hlt">transport</span> and reliability of these materials are important to study and understand. We report on a charge <span class="hlt">transport</span> model to predict leakage current and failure trends based on previously published data for a stoichiometric silicon nitride dielectric. Failure occurs when the defect density increases to a critical value of approximately 6 × 1025 traps/m3. The model's parameters are determined using voltage ramp data only, and yet, the model is also able to predict constant voltage stress failure over a time scale ranging from minutes to months. The successful fit of the model to the experimental data validates our assumption that the dominant defect in the dielectric is the Si dangling bond, located approximately 2.2 eV below the conduction band. A comparison with previous SiCOH simulations shows SiN and SiCOH have similar defect-related material properties. It is also speculated that, based on the estimated parameter values of 2.75 eV for the defect formation activation energy, the materials' TDDB wear-out are caused by broken Si-H bonds, resulting in Si dangling bond defects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24061333','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24061333"><span><span class="hlt">Electron</span> <span class="hlt">transport</span> through 5-substituted pyrimidines in DNA: <span class="hlt">electron</span> affinities of uracil and cytosine derivatives differently affect the apparent efficiencies.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ito, Takeo; Kurihara, Ryohsuke; Utsumi, Nihiro; Hamaguchi, Yuta; Tanabe, Kazuhito; Nishimoto, Sei-ichi</p> <p>2013-11-11</p> <p>We investigated excess <span class="hlt">electron</span> <span class="hlt">transport</span> (EET) in DNA containing cytosine derivatives. By arranging the derivatives according to their <span class="hlt">electron</span> affinities, the apparent EET efficiency was successfully regulated. Unexpectedly, however, providing gradients of <span class="hlt">electron</span> affinity by inserting 5-fluorocytosine did not always enhance EET.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SPIE.9458E..0HA','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SPIE.9458E..0HA"><span>Cyber warfare and <span class="hlt">electronic</span> warfare integration in the operational <span class="hlt">environment</span> of the future: cyber <span class="hlt">electronic</span> warfare</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Askin, Osman; Irmak, Riza; Avsever, Mustafa</p> <p>2015-05-01</p> <p>For the states with advanced technology, effective use of <span class="hlt">electronic</span> warfare and cyber warfare will be the main determining factor of winning a war in the future's operational <span class="hlt">environment</span>. The developed states will be able to finalize the struggles they have entered with a minimum of human casualties and minimum cost thanks to high-tech. Considering the increasing number of world economic problems, the development of human rights and humanitarian law it is easy to understand the importance of minimum cost and minimum loss of human. In this paper, cyber warfare and <span class="hlt">electronic</span> warfare concepts are examined in conjunction with the historical development and the relationship between them is explained. Finally, assessments were carried out about the use of cyber <span class="hlt">electronic</span> warfare in the coming years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA199700','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA199700"><span>Monte Carlo Studies of Nonlinear <span class="hlt">Electron</span> <span class="hlt">Transport</span> in III-V semiconductors</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1988-01-01</p> <p><span class="hlt">ELECTRON</span> <span class="hlt">TRANSPORT</span> IN III-V SEMICONDUCTORS DTIC Ki Wook Kim EL, .4 .SEP2 3198 H UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAICIN Approved for Public Release... semiconductors , GaAs/AlGaAs materia * system, Nonequilibrium situations, Monte Carlo simulation method, Analysis of <span class="hlt">transport</span> properties, Semiclassical...Boltzmar k. £8TRACT Contfinue on verse Inecesar. and ideneity by bloci, n,Mbr, <span class="hlt">transport</span> picture. <span class="hlt">Electron</span> <span class="hlt">transport</span> in III-V semiconductors , especially the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013CoTPh..59..121B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013CoTPh..59..121B"><span>Simulation Study of the <span class="hlt">Electron</span> and Hole <span class="hlt">Transport</span> in a CNTFET</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bahari, A.; Amiri, M.</p> <p>2013-01-01</p> <p>In this work we have investigated <span class="hlt">electron</span> and hole <span class="hlt">transport</span> through zig zag carbon nanotubes by solving Boltzmann <span class="hlt">Transport</span> Equation (BTE). We find that the mobility of <span class="hlt">electrons</span> is rather greater than holes. Carbo nanotubes with longer diameter can carry higher current. Normally, <span class="hlt">transport</span> of <span class="hlt">electrons</span> (or holes) is dominated by scattering events, which relax the carrier momentum in an effort to bring the conducting material to equilibrium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1334256','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1334256"><span><span class="hlt">Electron</span> <span class="hlt">Transport</span> Modeling of Molecular Nanoscale Bridges Used in Energy Conversion Schemes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Dunietz, Barry D</p> <p>2016-08-09</p> <p>The goal of the research program is to reliably describe <span class="hlt">electron</span> <span class="hlt">transport</span> and transfer processes at the molecular level. Such insight is essential for improving molecular applications of solar and thermal energy conversion. We develop <span class="hlt">electronic</span> structure models to study (1) photoinduced <span class="hlt">electron</span> transfer and <span class="hlt">transport</span> processes in organic semiconducting materials, and (2) charge and heat <span class="hlt">transport</span> through molecular bridges. We seek fundamental understanding of key processes, which lead to design new experiments and ultimately to achieve systems with improved properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1287449','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1287449"><span><span class="hlt">Electron</span> <span class="hlt">Transport</span> Modeling of Molecular Nanoscale Bridges Used in Energy Conversion Schemes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Dunietz, Barry D.</p> <p>2016-08-09</p> <p>The goal of the research program is to reliably describe <span class="hlt">electron</span> <span class="hlt">transport</span> and transfer processes at the molecular level. Such insight is essential for improving molecular applications of solar and thermal energy conversion. We develop <span class="hlt">electronic</span> structure models to study (1) photoinduced <span class="hlt">electron</span> transfer and <span class="hlt">transport</span> processes in organic semiconducting materials, and (2) charge and heat <span class="hlt">transport</span> through molecular bridges. We seek fundamental understanding of key processes, which lead to design new experiments and ultimately to achieve systems with improved properties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title32-vol6/pdf/CFR-2013-title32-vol6-sec2001-23.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title32-vol6/pdf/CFR-2013-title32-vol6-sec2001-23.pdf"><span>32 CFR 2001.23 - Classification marking in the <span class="hlt">electronic</span> <span class="hlt">environment</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... <span class="hlt">environment</span>. 2001.23 Section 2001.23 National Defense Other Regulations Relating to National Defense... <span class="hlt">environment</span>. (a) General. Classified national security information in the <span class="hlt">electronic</span> <span class="hlt">environment</span> shall be: (1... <span class="hlt">electronic</span> <span class="hlt">environment</span> cannot be marked in this manner, a warning shall be applied to alert users that the...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title32-vol6/pdf/CFR-2010-title32-vol6-sec2001-23.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title32-vol6/pdf/CFR-2010-title32-vol6-sec2001-23.pdf"><span>32 CFR 2001.23 - Classification marking in the <span class="hlt">electronic</span> <span class="hlt">environment</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... <span class="hlt">environment</span>. 2001.23 Section 2001.23 National Defense Other Regulations Relating to National Defense... <span class="hlt">environment</span>. (a) General. Classified national security information in the <span class="hlt">electronic</span> <span class="hlt">environment</span> shall be: (1... <span class="hlt">electronic</span> <span class="hlt">environment</span> cannot be marked in this manner, a warning shall be applied to alert users that the...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title32-vol6/pdf/CFR-2014-title32-vol6-sec2001-23.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title32-vol6/pdf/CFR-2014-title32-vol6-sec2001-23.pdf"><span>32 CFR 2001.23 - Classification marking in the <span class="hlt">electronic</span> <span class="hlt">environment</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>... <span class="hlt">environment</span>. 2001.23 Section 2001.23 National Defense Other Regulations Relating to National Defense... <span class="hlt">environment</span>. (a) General. Classified national security information in the <span class="hlt">electronic</span> <span class="hlt">environment</span> shall be: (1... <span class="hlt">electronic</span> <span class="hlt">environment</span> cannot be marked in this manner, a warning shall be applied to alert users that the...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title32-vol6/pdf/CFR-2012-title32-vol6-sec2001-23.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title32-vol6/pdf/CFR-2012-title32-vol6-sec2001-23.pdf"><span>32 CFR 2001.23 - Classification marking in the <span class="hlt">electronic</span> <span class="hlt">environment</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... <span class="hlt">environment</span>. 2001.23 Section 2001.23 National Defense Other Regulations Relating to National Defense... <span class="hlt">environment</span>. (a) General. Classified national security information in the <span class="hlt">electronic</span> <span class="hlt">environment</span> shall be: (1... <span class="hlt">electronic</span> <span class="hlt">environment</span> cannot be marked in this manner, a warning shall be applied to alert users that the...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title32-vol6/pdf/CFR-2011-title32-vol6-sec2001-23.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title32-vol6/pdf/CFR-2011-title32-vol6-sec2001-23.pdf"><span>32 CFR 2001.23 - Classification marking in the <span class="hlt">electronic</span> <span class="hlt">environment</span>.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... <span class="hlt">environment</span>. 2001.23 Section 2001.23 National Defense Other Regulations Relating to National Defense... <span class="hlt">environment</span>. (a) General. Classified national security information in the <span class="hlt">electronic</span> <span class="hlt">environment</span> shall be: (1... <span class="hlt">electronic</span> <span class="hlt">environment</span> cannot be marked in this manner, a warning shall be applied to alert users that the...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5161610','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5161610"><span>Mass transfer and <span class="hlt">transport</span> in a geologic <span class="hlt">environment</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chambre, P.L.; Pigford, T.H.; Lee, W.W.L.; Ahn, J.; Kajiwara, S.; Kim, C.L.; Kimura, H.; Lung, H.; Williams, W.J.; Zavoshy, S.J.</p> <p>1985-04-01</p> <p>This report is in a continuing series of reports that present analytic solutions for the dissolution and hydrogeologic <span class="hlt">transport</span> of radionuclides from geologic repositories of nuclear waste. Previous reports have dealt mainly with radionuclide <span class="hlt">transport</span> in the far-field, away from the effects of the repository. In the present report, the emphasis is on near-field processes, the transfer and <span class="hlt">transport</span> of radionuclides in the vicinity of the waste packages. The primary tool used in these analyses is mass transfer theory from chemical engineering. The thrust of our work is to develop methods for predicting the performance of geologic repositories. The subjects treated in the present report are: radionuclide <span class="hlt">transport</span> from a spherical-equivalent waste form through a backfill; analysis of radionuclide <span class="hlt">transport</span> through a backfill using a non-linear sorption isotherm; radionuclide <span class="hlt">transport</span> from a prolate spheroid-equivalent waste form with a backfill; radionuclide <span class="hlt">transport</span> from a spherical-equivalent waste form through a backfill, where the solubility, diffusivity and retardation coefficients are temperature dependent; a coupled near-field, far-field analysis where dissolution and migration rates are temperature dependent; <span class="hlt">transport</span> of radionuclides from a point source in a three-dimensional flow field; and a general solution for the <span class="hlt">transport</span> of radioactive chains in geologic media. There are several important results from the numerical evaluations. First, radioactive decay, higher sorption in the rock and the backfill steepens the gradient for mass transfer, and lead to higher dissolution rates. This is contrary to what was expected by some other workers, but is shown clearly in the analytical solutions. Second, the backfill serves to provide sorption sites so that there is a delay in the arrival of radionuclides in the rock, although this effect is not so important for the steady-state <span class="hlt">transport</span> of long-lived radionuclides.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21612067','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21612067"><span><span class="hlt">Electron</span> Capture Reactions and Beta Decays in Steller <span class="hlt">Environments</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Suzuki, T.; Mao, H.; Honma, M.; Yoshida, T.; Kajino, T.; Otsuka, T.</p> <p>2011-10-28</p> <p><span class="hlt">Electron</span> capture reactions on Ni and Co isotopes are investigated by shell model calculations in steller <span class="hlt">environments</span>. The capture rates depend sensitively on the distribution of the Gamow-Teller (GT) strength. The capture rates obtained by using GXPF1J Hamiltonian for fp-shell are found to be consistent with the rates obtained from experimental GT strength in {sup 58}Ni and {sup 60}Ni. Capture rates in Co isotopes, where there were large discrepancies among previous calculations, are also investigated. Beta decays of the N = 126 isotones are studied by shell model calculations taking into account both the GT and first-forbidden (FF) transitions. The FF transitions are found to be important to reduce the half-lives by twice to several times of those by the GT contributions only. Implications of the short half-lives of the waiting point nuclei on the r-process nucleosynthesis are discussed for various astrophysical conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23176467','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23176467"><span>A long way to the electrode: how do Geobacter cells <span class="hlt">transport</span> their <span class="hlt">electrons</span>?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bonanni, Pablo Sebastián; Schrott, Germán David; Busalmen, Juan Pablo</p> <p>2012-12-01</p> <p>The mechanism of <span class="hlt">electron</span> <span class="hlt">transport</span> in Geobacter sulfurreducens biofilms is a topic under intense study and debate. Although some proteins were found to be essential for current production, the specific role that each one plays in <span class="hlt">electron</span> <span class="hlt">transport</span> to the electrode remains to be elucidated and a consensus on the mechanism of <span class="hlt">electron</span> <span class="hlt">transport</span> has not been reached. In the present paper, to understand the state of the art in the topic, <span class="hlt">electron</span> <span class="hlt">transport</span> from inside of the cell to the electrode in Geobacter sulfurreducens biofilms is analysed, reviewing genetic studies, biofilm conductivity assays and electrochemical and spectro-electrochemical experiments. Furthermore, crucial data still required to achieve a deeper understanding are highlighted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/4343822','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/4343822"><span>Effect of pyrrolnitrin on <span class="hlt">electron</span> <span class="hlt">transport</span> and oxidative phosphorylation in mitochondria isolated from Neurospora crassa.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lambowitz, A M; Slayman, C W</p> <p>1972-11-01</p> <p>Pyrrolnitrin, at low concentrations, uncouples oxidative phosphorylation in Neurospora mitochondria. At higher concentrations, pyrrolnitrin inhibits <span class="hlt">electron</span> <span class="hlt">transport</span> both in the flavine region and through cytochrome oxidase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=251518','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=251518"><span>Effect of Pyrrolnitrin on <span class="hlt">Electron</span> <span class="hlt">Transport</span> and Oxidative Phosphorylation in Mitochondria Isolated from Neurospora crassa</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lambowitz, Alan M.; Slayman, Carolyn W.</p> <p>1972-01-01</p> <p>Pyrrolnitrin, at low concentrations, uncouples oxidative phosphorylation in Neurospora mitochondria. At higher concentrations, pyrrolnitrin inhibits <span class="hlt">electron</span> <span class="hlt">transport</span> both in the flavine region and through cytochrome oxidase. PMID:4343822</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21373893','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21373893"><span>Mechanism of action of anions on the <span class="hlt">electron</span> <span class="hlt">transport</span> chain in thylakoid membranes of higher plants.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Singh-Rawal, Pooja; Zsiros, Ottó; Bharti, Sudhakar; Garab, Gyozo; Jajoo, Anjana</p> <p>2011-04-01</p> <p>With an aim to improve our understanding of the mechanisms behind specific anion effects in biological membranes, we have studied the effects of sodium salts of anions of varying valency in thylakoid membranes. Rates of <span class="hlt">electron</span> <span class="hlt">transport</span> of PS II and PS I, 77K fluorescence emission and excitation spectra, cyclic <span class="hlt">electron</span> flow around PS I and circular dichroism (CD) spectra were measured in thylakoid membranes in order to elucidate a general mechanism of action of inorganic anions on photosynthetic <span class="hlt">electron</span> <span class="hlt">transport</span> chain. Re-distribution of absorbed excitation energy has been observed as a signature effect of inorganic anions. In the presence of anions, such as nitrite, sulphate and phosphate, distribution of absorbed excitation energy was found to be more in favor of Photosystem I (PS I). The amount of energy distributed towards PS I depended on the valency of the anion. In this paper, we propose for the first time that energy re-distribution and its valence dependence may not be the effect of anions per se. The entry of negative charge (anion) is accompanied by influx of positive charge (protons) to maintain a balance of charge across the thylakoid membranes. As reflected by the CD spectra, the observed energy re-distribution could be a result of structural rearrangements of the protein complexes of PS II caused by changes in the ionic <span class="hlt">environment</span> of the thylakoid lumen.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT.......276M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT.......276M"><span><span class="hlt">Transport</span> of Zinc Oxide Nanoparticles in a Simulated Gastric <span class="hlt">Environment</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mayfield, Ryan T.</p> <p></p> <p>Recent years have seen a growing interest in the use of many types of nano sized materials in the consumer sector. Potential uses include encapsulation of nutrients, providing antimicrobial activity, altering texture, or changing bioavailability of nutrients. Engineered nanoparticles (ENP) possess properties that are different than larger particles made of the same constituents. Properties such as solubility, aggregation state, and toxicity can all be changed as a function of size. The gastric <span class="hlt">environment</span> is an important area for study of engineered nanoparticles because of the varied physical, chemical, and enzymatic processes that are prevalent there. These all have the potential to alter those properties of ENP that make them different from their bulk counterparts. The Human Gastric Simulator (HGS) is an advanced in vitro model that can be used to study many facets of digestion. The HGS consists of a plastic lining that acts as the stomach cavity with two sets of U-shaped arms on belts that provide the physical forces needed to replicate peristalsis. Altering the position of the arms or changing the speed of the motor which powers them allows one to tightly hone and replicate varied digestive conditions. Gastric juice, consisting of salts, enzymes, and acid levels which replicate physiological conditions, is introduced to the cavity at a controllable rate. The release of digested food from the lumen of simulated stomach is controlled by a peristaltic pump. The goal of the HGS is to accurately and repeatedly simulate human digestion. This study focused on introducing foods spiked with zinc oxide ENP and bulk zinc oxide into the HGS and then monitoring how the concentration of each changed at two locations in the HGS over a two hour period. The two locations chosen were the highest point in the lumen of the stomach, which represented the fundus, and a point just beyond the equivalent of the pylorus, which represented the antrum of the stomach. These points were</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998JAP....83.3207B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998JAP....83.3207B"><span><span class="hlt">Electron</span> <span class="hlt">transport</span> across metal/discotic liquid crystal interfaces</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Boden, N.; Bushby, R. J.; Clements, J.; Movaghar, B.</p> <p>1998-03-01</p> <p><span class="hlt">Electron</span> <span class="hlt">transport</span> across micron thick films of columnar hexagonal discotic liquid crystal phases homeotropically aligned between metal electrode surfaces has been studied both experimentally and theoretically. These molecules are unique in their combination of charge <span class="hlt">transport</span> along individual molecular columns with liquidlike self-organization. Typical of organic insulators, a high resistance Ohmic regime is evident at fields of less than 0.05 MV cm-1, due to a low concentration of chemical impurities (n<109cm-3), and a space-charge injection regime at higher fields. Breakdown fields are reasonably high: in hexakis(hexyloxy)triphenylene they reach ˜5 MV cm-1 at room temperature. Our results show that triphenylene-based discotics form an excellent class of highly ordered optically transparent insulators. At high temperatures and high fields the current is injection controlled and exhibits typical tunneling and space charge limited, nonlinear I-V characteristics. Dramatic jumps in injection currents are observed at phase transitions. The change at the crystalline to liquid crystalline phase transition is mainly due to more efficient "wetting" of the electrode surface in the liquid crystalline phase, whilst at the liquid crystalline to isotropic phase transition it arises from the enhancement in the molecular mobility. The concepts of semiconducting gaps, band mobilities, and carrier injection rates are extended to these new materials. The experimental observations are interpreted in a framework which takes into account the important role played by liquidlike dynamics in establishing the microscopic structural order in, what is, otherwise a highly anisotropic and weakly bonded "molecular crystal."</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050169213','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050169213"><span>Energetic <span class="hlt">Electron</span> <span class="hlt">Transport</span> in the Inner Magnetosphere During Geomagnetic Storms and Substorms</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>McKenzie, D. L.; Anderson, P. C.</p> <p>2005-01-01</p> <p>We propose to examine the relationship of geomagnetic storms and substorms and the <span class="hlt">transport</span> of energetic particles in the inner magnetosphere using measurements of the auroral X-ray emissions by PIXIE. PIXIE provides a global view of the auroral oval for the extended periods of time required to study stormtime phenomena. Its unique energy response and global view allow separation of stormtime particle <span class="hlt">transport</span> driven by strong magnetospheric electric fields from substorm particle <span class="hlt">transport</span> driven by magnetic-field dipolarization and subsequent particle injection. The relative importance of substorms in releasing stored magnetospheric energy during storms and injecting particles into the inner magnetosphere and the ring current is currently hotly debated. The distribution of particles in the inner magnetosphere is often inferred from measurements of the precipitating auroral particles. Thus, the global distributions of the characteristics of energetic precipitating particles during storms and substorms are extremely important inputs to any description or model of the geospace <span class="hlt">environment</span> and the Sun-Earth connection. We propose to use PIXIE observations and modeling of the <span class="hlt">transport</span> of energetic <span class="hlt">electrons</span> to examine the relationship between storms and substorms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPS...320..343H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPS...320..343H"><span>Quantification of ionic <span class="hlt">transport</span> within thermally-activated batteries using <span class="hlt">electron</span> probe micro-analysis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Humplik, Thomas; Stirrup, Emily K.; Grillet, Anne M.; Grant, Richard P.; Allen, Ashley N.; Wesolowski, Daniel E.; Roberts, Christine C.</p> <p>2016-07-01</p> <p>The transient <span class="hlt">transport</span> of electrolytes in thermally-activated batteries is studied using <span class="hlt">electron</span> probe micro-analysis (EPMA), demonstrating the robust capability of EPMA as a useful tool for studying and quantifying mass <span class="hlt">transport</span> within porous materials, particularly in difficult <span class="hlt">environments</span> where classical flow measurements are challenging. By tracking the mobility of bromine and potassium ions from the electrolyte stored within the separator into the lithium silicon anode and iron disulfide cathode, we are able to quantify the <span class="hlt">transport</span> mechanisms and physical properties of the electrodes including permeability and tortuosity. Due to the micron to submicron scale porous structure of the initially dry anode, a fast capillary pressure driven flow is observed into the anode from which we are able to set a lower bound on the permeability of 10-1 mDarcy. The <span class="hlt">transport</span> into the cathode is diffusion-limited because the cathode originally contained some electrolyte before activation. Using a transient one-dimensional diffusion model, we estimate the tortuosity of the cathode electrode to be 2.8 ± 0.8.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060051442&hterms=extreme+running&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dextreme%2Brunning','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060051442&hterms=extreme+running&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dextreme%2Brunning"><span>Reconfiguration of Analog <span class="hlt">Electronics</span> for Extreme <span class="hlt">Environments</span>: Problem or Solution?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stoica, Adrian; Zebulum, Ricardo; Keymeulen, Didier; Guo, Xin</p> <p>2005-01-01</p> <p>This paper argues in favor of adaptive reconfiguration as a technique to expand the operational envelope of analog <span class="hlt">electronics</span> for extreme <span class="hlt">environments</span> (EE). In addition to hardening-by-process and hardening-by-design, "hardening-by-reconfiguration", when applicable, could be used to mitigate drifts, degradation, or damage on <span class="hlt">electronic</span> devices (chips) in EE, by using re-configurable devices and an adaptive self-reconfiguration of their circuit topology. Conventional circuit design exploits device characteristics within a certain temperature/radiation range; when that is exceeded, the circuit function degrades. On a reconfigurable device, although component parameters change in EE, as long as devices still operate, albeit degraded, a new circuit design, suitable for new parameter values, may be mapped into the reconfigurable structure to recover the initial circuit function. Partly degraded resources are still used, while completely damaged resources are bypassed. Designs suitable for various environmental conditions can be determined prior to operation or can be determined in-situ, by adaptive reconfiguration algorithms running on built-in digital controllers. Laboratory demonstrations of this technique were performed by JPL in several independent experiments in which bulk CMOS reconfigurable devices were exposed to, and degraded by, low temperatures (approx. 196 C), high temperatures (approx.300 C) or radiation (300kRad TID), and then recovered by adaptive reconfiguration using evolutionary search algorithms. Taking this technology from Technology Readiness Level (TRL) 3 to TRL 5 is the target of a current NASA project.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060051442&hterms=analog+design&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Danalog%2Bdesign','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060051442&hterms=analog+design&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Danalog%2Bdesign"><span>Reconfiguration of Analog <span class="hlt">Electronics</span> for Extreme <span class="hlt">Environments</span>: Problem or Solution?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stoica, Adrian; Zebulum, Ricardo; Keymeulen, Didier; Guo, Xin</p> <p>2005-01-01</p> <p>This paper argues in favor of adaptive reconfiguration as a technique to expand the operational envelope of analog <span class="hlt">electronics</span> for extreme <span class="hlt">environments</span> (EE). In addition to hardening-by-process and hardening-by-design, "hardening-by-reconfiguration", when applicable, could be used to mitigate drifts, degradation, or damage on <span class="hlt">electronic</span> devices (chips) in EE, by using re-configurable devices and an adaptive self-reconfiguration of their circuit topology. Conventional circuit design exploits device characteristics within a certain temperature/radiation range; when that is exceeded, the circuit function degrades. On a reconfigurable device, although component parameters change in EE, as long as devices still operate, albeit degraded, a new circuit design, suitable for new parameter values, may be mapped into the reconfigurable structure to recover the initial circuit function. Partly degraded resources are still used, while completely damaged resources are bypassed. Designs suitable for various environmental conditions can be determined prior to operation or can be determined in-situ, by adaptive reconfiguration algorithms running on built-in digital controllers. Laboratory demonstrations of this technique were performed by JPL in several independent experiments in which bulk CMOS reconfigurable devices were exposed to, and degraded by, low temperatures (approx. 196 C), high temperatures (approx.300 C) or radiation (300kRad TID), and then recovered by adaptive reconfiguration using evolutionary search algorithms. Taking this technology from Technology Readiness Level (TRL) 3 to TRL 5 is the target of a current NASA project.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=vehicular+AND+pollution&id=ED147590','ERIC'); return false;" href="http://eric.ed.gov/?q=vehicular+AND+pollution&id=ED147590"><span><span class="hlt">Transportation</span> and the <span class="hlt">Environment</span> in Harmony: Mini-Units and Learning Activities for Grades 9 through 12.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Finn, Peter; And Others</p> <p></p> <p>One of a series of eleven curriculum manuals which cover the four <span class="hlt">transportation</span> topics of public <span class="hlt">transportation</span>, <span class="hlt">transportation</span> and the <span class="hlt">environment</span>, <span class="hlt">transportation</span> safety, and bicycles for elementary, secondary, and adult levels, this manual covers the <span class="hlt">transportation</span> and the <span class="hlt">environment</span> topic for grades 9-12. It contains forty-four learning…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=vehicular+AND+pollution&id=ED147589','ERIC'); return false;" href="http://eric.ed.gov/?q=vehicular+AND+pollution&id=ED147589"><span><span class="hlt">Transportation</span> and the <span class="hlt">Environment</span> in Harmony: Mini-Units and Learning Activities for Grades 6 through 9.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Finn, Peter; And Others</p> <p></p> <p>One of a series of eleven curriculum manuals which cover the four <span class="hlt">transportation</span> topics of public <span class="hlt">transportation</span>, <span class="hlt">transportation</span> and the <span class="hlt">environment</span>, <span class="hlt">transportation</span> safety, and bicycles for elementary, secondary, and adult levels, this manual covers the <span class="hlt">transportation</span> and the <span class="hlt">environment</span> topic for grades 6-9. It contains thirty-nine learning…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22304308','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22304308"><span>Local atomic order, <span class="hlt">electronic</span> structure and <span class="hlt">electron</span> <span class="hlt">transport</span> properties of Cu-Zr metallic glasses</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Antonowicz, J. Pietnoczka, A.; Pękała, K.; Latuch, J.; Evangelakis, G. A.</p> <p>2014-05-28</p> <p>We studied atomic and <span class="hlt">electronic</span> structures of binary Cu-Zr metallic glasses (MGs) using combined experimental and computational methods including X-ray absorption fine structure spectroscopy, electrical resistivity, thermoelectric power (TEP) measurements, molecular dynamics (MD) simulations, and ab-initio calculations. The results of MD simulations and extended X-ray absorption fine structure analysis indicate that atomic order of Cu-Zr MGs and can be described in terms of interpenetrating icosahedral-like clusters involving five-fold symmetry. MD configurations were used as an input for calculations of theoretical <span class="hlt">electronic</span> density of states (DOS) functions which exhibits good agreement with the experimental X-ray absorption near-edge spectra. We found no indication of minimum of DOS at Fermi energy predicted by Mott's nearly free <span class="hlt">electron</span> (NFE) model for glass-forming alloys. The theoretical DOS was subsequently used to test Mott's model describing the temperature variation of electrical resistivity and thermoelectric power of transition metal-based MGs. We demonstrate that the measured temperature variations of electrical resistivity and TEP remain in a contradiction with this model. On the other hand, the experimental temperature dependence of electrical resistivity can be explained by incipient localization of conduction <span class="hlt">electrons</span>. It is shown that weak localization model works up to relatively high temperatures when localization is destroyed by phonons. Our results indicate that <span class="hlt">electron</span> <span class="hlt">transport</span> properties of Cu-Zr MGs are dominated by localization effects rather than by <span class="hlt">electronic</span> structure. We suggest that NFE model fails to explain a relatively high glass-forming ability of binary Cu-Zr alloys.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JAP...115t3714A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JAP...115t3714A"><span>Local atomic order, <span class="hlt">electronic</span> structure and <span class="hlt">electron</span> <span class="hlt">transport</span> properties of Cu-Zr metallic glasses</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Antonowicz, J.; Pietnoczka, A.; Pekała, K.; Latuch, J.; Evangelakis, G. A.</p> <p>2014-05-01</p> <p>We studied atomic and <span class="hlt">electronic</span> structures of binary Cu-Zr metallic glasses (MGs) using combined experimental and computational methods including X-ray absorption fine structure spectroscopy, electrical resistivity, thermoelectric power (TEP) measurements, molecular dynamics (MD) simulations, and ab-initio calculations. The results of MD simulations and extended X-ray absorption fine structure analysis indicate that atomic order of Cu-Zr MGs and can be described in terms of interpenetrating icosahedral-like clusters involving five-fold symmetry. MD configurations were used as an input for calculations of theoretical <span class="hlt">electronic</span> density of states (DOS) functions which exhibits good agreement with the experimental X-ray absorption near-edge spectra. We found no indication of minimum of DOS at Fermi energy predicted by Mott's nearly free <span class="hlt">electron</span> (NFE) model for glass-forming alloys. The theoretical DOS was subsequently used to test Mott's model describing the temperature variation of electrical resistivity and thermoelectric power of transition metal-based MGs. We demonstrate that the measured temperature variations of electrical resistivity and TEP remain in a contradiction with this model. On the other hand, the experimental temperature dependence of electrical resistivity can be explained by incipient localization of conduction <span class="hlt">electrons</span>. It is shown that weak localization model works up to relatively high temperatures when localization is destroyed by phonons. Our results indicate that <span class="hlt">electron</span> <span class="hlt">transport</span> properties of Cu-Zr MGs are dominated by localization effects rather than by <span class="hlt">electronic</span> structure. We suggest that NFE model fails to explain a relatively high glass-forming ability of binary Cu-Zr alloys.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Nanot..27H5503P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Nanot..27H5503P"><span>Surface trap mediated <span class="hlt">electronic</span> <span class="hlt">transport</span> in biofunctionalized silicon nanowires</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Puppo, F.; Traversa, F. L.; Di Ventra, M.; De Micheli, G.; Carrara, S.</p> <p>2016-08-01</p> <p>Silicon nanowires (SiNWs), fabricated via a top-down approach and then functionalized with biological probes, are used for electrically-based sensing of breast tumor markers. The SiNWs, featuring memristive-like behavior in bare conditions, show, in the presence of biomarkers, modified hysteresis and, more importantly, a voltage memory component, namely a voltage gap. The voltage gap is demonstrated to be a novel and powerful parameter of detection thanks to its high-resolution dependence on charges in proximity of the wire. This unique approach of sensing has never been studied and adopted before. Here, we propose a physical model of the surface <span class="hlt">electronic</span> <span class="hlt">transport</span> in Schottky barrier SiNW biosensors, aiming at reproducing and understanding the voltage gap based behavior. The implemented model describes well the experimental I-V characteristics of the device. It also links the modification of the voltage gap to the changing concentration of antigens by showing the decrease of this parameter in response to increasing concentrations of the molecules that are detected with femtomolar resolution in real human samples. Both experiments and simulations highlight the predominant role of the dynamic recombination of the nanowire surface states, with the incoming external charges from bio-species, in the appearance and modification of the voltage gap. Finally, thanks to its compactness, and strict correlation with the physics of the nanodevice, this model can be used to describe and predict the I-V characteristics in other nanostructured devices, for different than antibody-based sensing as well as <span class="hlt">electronic</span> applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22341856','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22341856"><span>Study of <span class="hlt">electronic</span> <span class="hlt">transport</span> in gamma ray exposed nanowires</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gehlawat, Devender Chauhan, R.P.</p> <p>2014-01-01</p> <p>Graphical abstract: A sharp decline in the I–V characteristics of Cu (and Cd) nanowires was experimentally observed after the gamma ray exposure of nanowires. Irradiation induced transformations in the granular properties and the resonance state of electron–phonon coupling beyond a particular value of external field may be accountable for observed shape of I–V characteristics in gamma ray exposed nanowires. - Highlights: • Cu and Cd nanowires were synthesized by technique of electrodeposition in templates. • The nanowires were exposed to different doses of gamma ray photons. • A sharp decline in the current in I–V characteristics (IVC) was observed. • Structural deviation in terms of granular orientations was also analysed. • The electron–phonon coupling may be responsible for observed sharp decline in IVC. - Abstract: One dimensional nanostructures provide the most restricted and narrow channel for the <span class="hlt">transport</span> of charge carriers and therefore 1D structures preserve their significance from the viewpoint of <span class="hlt">electronic</span> devices. The net radiation effect on nanomaterials is expected to be more (due to their increased reactivity and lesser bulk volume) than their bulk counterparts. Radiation often modifies the structure and simultaneously the other physical properties of materials. In this manner, the irradiation phenomenon could be counted as a strong criterion to induce changes in the structural and electrical properties of nanowires. We have studied the effect of gamma rays on the <span class="hlt">electronic</span> flow through Cu and Cd nanowires by plotting their I–V characteristics (IVC). The IVC of gamma ray exposed nanowires was found to be a combination of the linear and nonlinear regions and a decreasing pattern in the electrical conductivity (calculated from the linear portion of IVC) was observed as we increased the dose of gamma rays.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17199353','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17199353"><span>Contact effects on <span class="hlt">electronic</span> <span class="hlt">transport</span> in donor-bridge-acceptor complexes interacting with a thermal bath.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Volkovich, Roie; Peskin, Uri</p> <p>2006-12-28</p> <p>A model for <span class="hlt">electron</span> transfer in donor-bridge-acceptor complexes with <span class="hlt">electronic</span> coupling to nuclear bridge modes is studied using the Redfield formulation. We demonstrate that the <span class="hlt">transport</span> mechanism through the molecular bridge is controlled by the location of the <span class="hlt">electronic</span>-nuclear coupling term along the bridge. As the <span class="hlt">electronic</span>-nuclear coupling term is shifted from the donor/acceptor-bridge contact sites into the bridge, the mechanism changes from kinetic <span class="hlt">transport</span> (incoherent, thermally activated, and bridge-length independent) to coherent tunneling oscillations. This study joins earlier works aiming to explore the factors which control the mechanism of <span class="hlt">electronic</span> <span class="hlt">transport</span> through molecular bridges and molecular wires.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/40204621','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/40204621"><span>Experimental Characterization of the <span class="hlt">Electron</span> Heat <span class="hlt">Transport</span> in Low-Density ASDEX Upgrade Plasmas</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ryter, F.; Imbeaux, F.; Leuterer, F.; Fahrbach, H.-U.; Suttrop, W.; ASDEX Upgrade Team</p> <p>2001-06-11</p> <p>The <span class="hlt">electron</span> heat <span class="hlt">transport</span> is investigated in ASDEX Upgrade conventional L -mode plasmas with pure <span class="hlt">electron</span> heating provided by <span class="hlt">electron</span>-cyclotron heating (ECH) at low density. Under these conditions, steady-state and ECH modulation experiments indicate without ambiguity that <span class="hlt">electron</span> heat <span class="hlt">transport</span> exhibits a clear threshold in {nabla}T{sub e}/T{sub e} and also suggest that it has a gyro-Bohm character.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15305511','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15305511"><span>Survey of <span class="hlt">transport</span> <span class="hlt">environments</span> of circus tigers (Panthera tigris).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nevill, Christian H; Friend, Ted H; Toscano, Michael J</p> <p>2004-06-01</p> <p>The type of equipment used to <span class="hlt">transport</span> circus tigers, environmental factors experienced during <span class="hlt">transport</span>, and resultant body temperatures of tigers <span class="hlt">transported</span> were surveyed during hot and cold weather conditions with six different circus tiger acts. Dataloggers recorded interior and exterior temperatures, relative humidity, and radiant heat at 5-min intervals during each trip. Microdataloggers fed to the tigers recorded body temperature and were recovered from eight Bengal (Panthera tigris tigris), Siberian (P. t. altaica), or Bengal-Sumatran (P. t. tigris-P. t. sumatrae) cross tigers from four different circuses. Three basic types of systems were used by circus acts to <span class="hlt">transport</span> tigers: freestanding cages mounted on wheels that were winched or pushed into a semitrailer for <span class="hlt">transport</span>, cages built into the trailer itself, and weather-resistant units <span class="hlt">transported</span> on flatbed railcars or flatbed truck trailers. The highest temperature encountered inside a trailer was 37.3 degrees C in hot weather conditions, but overall, temperatures were usually between 21.1-26.7 degrees C. Temperature inside the trailers did not appear to be affected by movement and did not generally exceed ambient temperatures, indicating adequate insulation and passive ventilation. During cold weather trips, the lowest temperature inside the trailers was -1.1 degrees C, occurring during an overnight stop. Interior temperatures during cold weather <span class="hlt">transport</span> stayed 2-6 degrees C warmer than ambient temperatures. The body temperatures of the tigers were unaffected by extreme temperatures. The only changes observed in body temperature were increases of 1-2 degrees C caused by activity and excitement associated with loading in several groups of tigers, regardless of whether it was hot or cold weather. Whenever measured, carbon monoxide and ammonia were below the detectable concentrations of 10 and 1 ppm. respectively. Overall, <span class="hlt">transport</span> did not appear to have any adverse effects on the tigers' ability</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1185679-defect-mediated-transport-electronic-irradiation-effect-individual-domains-cvd-grown-monolayer-mos2','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1185679-defect-mediated-transport-electronic-irradiation-effect-individual-domains-cvd-grown-monolayer-mos2"><span>Defect-mediated <span class="hlt">transport</span> and <span class="hlt">electronic</span> irradiation effect in individual domains of CVD-grown monolayer MoS2</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Durand, Corentin; Zhang, Xiaoguang; Fowlkes, Jason; ...</p> <p>2015-01-16</p> <p>We study the electrical <span class="hlt">transport</span> properties of atomically thin individual crystalline grains of MoS2 with four-probe scanning tunneling microscopy. The monolayer MoS2 domains are synthesized by chemical vapor deposition on SiO2/Si substrate. Temperature dependent measurements on conductance and mobility show that <span class="hlt">transport</span> is dominated by an <span class="hlt">electron</span> charge trapping and thermal release process with very low carrier density and mobility. The effects of <span class="hlt">electronic</span> irradiation are examined by exposing the film to <span class="hlt">electron</span> beam in the scanning <span class="hlt">electron</span> microscope in an ultrahigh vacuum <span class="hlt">environment</span>. The irradiation process is found to significantly affect the mobility and the carrier density of themore » material, with the conductance showing a peculiar time-dependent relaxation behavior. It is suggested that the presence of defects in active MoS2 layer and dielectric layer create charge trapping sites, and a multiple trapping and thermal release process dictates the <span class="hlt">transport</span> and mobility characteristics. The <span class="hlt">electron</span> beam irradiation promotes the formation of defects and impact the electrical properties of MoS2. Finally, our study reveals the important roles of defects and the <span class="hlt">electron</span> beam irradiation effects in the <span class="hlt">electronic</span> properties of atomic layers of MoS2.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26575923','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26575923"><span><span class="hlt">Electronic</span> Energy Transfer in Polarizable Heterogeneous <span class="hlt">Environments</span>: A Systematic Investigation of Different Quantum Chemical Approaches.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Steinmann, Casper; Kongsted, Jacob</p> <p>2015-09-08</p> <p>Theoretical prediction of <span class="hlt">transport</span> and optical properties of protein-pigment complexes is of significant importance when aiming at understanding the structure-function relationship in such systems. <span class="hlt">Electronic</span> energy transfer (EET) couplings represent a key property in this respect since such couplings provide important insight into the strength of interaction between photoactive pigments in protein-pigment complexes. Recently, attention has been payed to how the <span class="hlt">environment</span> modifies or even controls the <span class="hlt">electronic</span> couplings. To enable such theoretical predictions, a fully polarizable embedding model has been suggested (Curutchet, C., et al. J. Chem. Theory Comput., 2009, 5, 1838-1848). In this work, we further develop this computational model by extending it with an ab initio derived polarizable force field including higher-order multipole moments. We use this extended model to systematically examine three different ways of obtaining EET couplings in a heterogeneous medium ranging from use of the exact transition density to a point-dipole approximation. Several interesting observations are made, for example, the explicit use of transition densities in the calculation of the <span class="hlt">electronic</span> couplings, and also when including the explicit <span class="hlt">environment</span> contribution, can be replaced by a much simpler transition point charge description without comprising the quality of the model predictions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DPPPI3002M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DPPPI3002M"><span><span class="hlt">Electron</span> turbulence and <span class="hlt">transport</span> in large magnetic islands</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Morton, Lucas</p> <p>2016-10-01</p> <p>Magnetic islands, observed in both reversed-field pinches (RFPs) and tokamaks, often display unexpected turbulence and <span class="hlt">transport</span> characteristics. For the first time in an RFP, the high repetition rate Thomson scattering diagnostic on MST has captured a 2D image of the rotating <span class="hlt">electron</span> temperature structure of a magnetic island in a single discharge. MHD modeling using edge magnetic signals implies a 16 cm wide m,n =1,6 tearing mode island which completely overlaps a 5.5 cm n =7 island (12 cm between island centers). The 3D field is partially chaotic, but still reflective of the n =6 island structure. The measured temperature structure matches the shape and location of the n =6 partially chaotic (or `remnant') island. Contrary to the usual assumption that islands have flat internal temperature, the <span class="hlt">electron</span> temperature is peaked inside the remnant magnetic island due to ohmic heating. The temperature peaking implies a local effective perpendicular conductivity 10-40 m2/s inside the remnant island. This agrees quantitatively with an effective perpendicular conductivity of 16 m2/s estimated using the magnetic diffusion coefficient (evaluated at the <span class="hlt">electron</span> mean free path) calculated from the modeled chaotic field. Statistical analysis of measurement ensembles with lower time resolution implies that remnant island heating is common in MST discharges. To investigate the role of turbulence near a magnetic island, the 2D structure of long-wavelength density turbulence has been mapped around a large applied static m,n =2,1 L-mode island in the DIII-D tokamak. The turbulence exhibits intriguing spatial structure. Fluctuations are enhanced several-fold (compared to the no-island case) on the inboard side of the X-point, but not on the outboard side of the X-point and are also reduced near the O-point. This work is supported by the NSF and US DOE under DE-FC02-04ER54698, and DE-FG02-89ER53296.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1200859','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1200859"><span><span class="hlt">Electronic</span> <span class="hlt">transport</span> in two-dimensional high dielectric constant nanosystems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ortuño, M.; Somoza, A. M.; Vinokur, V. M.; Baturina, T. I.</p> <p>2015-04-10</p> <p>There has been remarkable recent progress in engineering high-dielectric constant two dimensional (2D) materials, which are being actively pursued for applications in nanoelectronics in capacitor and memory devices, energy storage, and high-frequency modulation in communication devices. Yet many of the unique properties of these systems are poorly understood and remain unexplored. Here we report a numerical study of hopping conductivity of the lateral network of capacitors, which models two-dimensional insulators, and demonstrate that 2D long-range Coulomb interactions lead to peculiar size effects. We find that the characteristic energy governing <span class="hlt">electronic</span> <span class="hlt">transport</span> scales logarithmically with either system size or electrostatic screening length depending on which one is shorter. Our results are relevant well beyond their immediate context, explaining, for example, recent experimental observations of logarithmic size dependence of electric conductivity of thin superconducting films in the critical vicinity of superconductor-insulator transition where a giant dielectric constant develops. Our findings mark a radical departure from the orthodox view of conductivity in 2D systems as a local characteristic of materials and establish its macroscopic global character as a generic property of high-dielectric constant 2D nanomaterials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1200859-electronic-transport-two-dimensional-high-dielectric-constant-nanosystems','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1200859-electronic-transport-two-dimensional-high-dielectric-constant-nanosystems"><span><span class="hlt">Electronic</span> <span class="hlt">transport</span> in two-dimensional high dielectric constant nanosystems</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Ortuño, M.; Somoza, A. M.; Vinokur, V. M.; ...</p> <p>2015-04-10</p> <p>There has been remarkable recent progress in engineering high-dielectric constant two dimensional (2D) materials, which are being actively pursued for applications in nanoelectronics in capacitor and memory devices, energy storage, and high-frequency modulation in communication devices. Yet many of the unique properties of these systems are poorly understood and remain unexplored. Here we report a numerical study of hopping conductivity of the lateral network of capacitors, which models two-dimensional insulators, and demonstrate that 2D long-range Coulomb interactions lead to peculiar size effects. We find that the characteristic energy governing <span class="hlt">electronic</span> <span class="hlt">transport</span> scales logarithmically with either system size or electrostatic screeningmore » length depending on which one is shorter. Our results are relevant well beyond their immediate context, explaining, for example, recent experimental observations of logarithmic size dependence of electric conductivity of thin superconducting films in the critical vicinity of superconductor-insulator transition where a giant dielectric constant develops. Our findings mark a radical departure from the orthodox view of conductivity in 2D systems as a local characteristic of materials and establish its macroscopic global character as a generic property of high-dielectric constant 2D nanomaterials.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6067078','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6067078"><span>Considerations of beta and <span class="hlt">electron</span> <span class="hlt">transport</span> in internal dose calculations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bolch, W.E.; Poston, J.W. Sr.</p> <p>1990-12-01</p> <p>Ionizing radiation has broad uses in modern science and medicine. These uses often require the calculation of energy deposition in the irradiated media and, usually, the medium of interest is the human body. Energy deposition from radioactive sources within the human body and the effects of such deposition are considered in the field of internal dosimetry. In July of 1988, a three-year research project was initiated by the Nuclear Engineering Department at Texas A M University under the sponsorship of the US Department of Energy. The main thrust of the research was to consider, for the first time, the detailed spatial <span class="hlt">transport</span> of <span class="hlt">electron</span> and beta particles in the estimation of average organ doses under the Medical Internal Radiation Dose (MIRD) schema. At the present time (December of 1990), research activities are continuing within five areas. Several are new initiatives begun within the second or third year of the current contract period. They include: (1) development of small-scale dosimetry; (2) development of a differential volume phantom; (3) development of a dosimetric bone model; (4) assessment of the new ICRP lung model; and (5) studies into the mechanisms of DNA damage. A progress report is given for each of these tasks within the Comprehensive Report. In each case, preliminary results are very encouraging and plans for further research are detailed within this document.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015NatSR...5E9667O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015NatSR...5E9667O"><span><span class="hlt">Electronic</span> <span class="hlt">transport</span> in two-dimensional high dielectric constant nanosystems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ortuño, M.; Somoza, A. M.; Vinokur, V. M.; Baturina, T. I.</p> <p>2015-04-01</p> <p>There has been remarkable recent progress in engineering high-dielectric constant two dimensional (2D) materials, which are being actively pursued for applications in nanoelectronics in capacitor and memory devices, energy storage, and high-frequency modulation in communication devices. Yet many of the unique properties of these systems are poorly understood and remain unexplored. Here we report a numerical study of hopping conductivity of the lateral network of capacitors, which models two-dimensional insulators, and demonstrate that 2D long-range Coulomb interactions lead to peculiar size effects. We find that the characteristic energy governing <span class="hlt">electronic</span> <span class="hlt">transport</span> scales logarithmically with either system size or electrostatic screening length depending on which one is shorter. Our results are relevant well beyond their immediate context, explaining, for example, recent experimental observations of logarithmic size dependence of electric conductivity of thin superconducting films in the critical vicinity of superconductor-insulator transition where a giant dielectric constant develops. Our findings mark a radical departure from the orthodox view of conductivity in 2D systems as a local characteristic of materials and establish its macroscopic global character as a generic property of high-dielectric constant 2D nanomaterials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvB..94w5448P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvB..94w5448P"><span>Spin-polarized <span class="hlt">electron</span> <span class="hlt">transport</span> through helicene molecular junctions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pan, Ting-Rui; Guo, Ai-Min; Sun, Qing-Feng</p> <p>2016-12-01</p> <p>Recently, the spin-selectivity effect of chiral molecules has been attracting extensive and growing interest among the scientific communities. Here, we propose a model Hamiltonian to study spin-dependent <span class="hlt">electron</span> <span class="hlt">transport</span> through helicene molecules which are connected by two semi-infinite graphene nanoribbons and try to elucidate a recent experiment of the spin-selectivity effect observed in the helicene molecules. The results indicate that the helicene molecules can present a significant spin-filtering effect in the case of extremely weak spin-orbit coupling, which is three orders of magnitude smaller than the hopping integral. The underlying physics is attributed to intrinsic chiral symmetry of the helicene molecules. When the chirality is switched from the right-handed species to the left-handed species, the spin polarization is reversed exactly. These results are consistent with a recent experiment [V. Kiran et al., Adv. Mater. 28, 1957 (2016), 10.1002/adma.201504725]. In addition, the spin-filtering effect of the helicene molecules is robust against molecular lengths, dephasing strengths, and space position disorder. This theoretical work may motivate further studies on chiral-induced spin selectivity in molecular systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...627049F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...627049F"><span>Defect engineering of the <span class="hlt">electronic</span> <span class="hlt">transport</span> through cuprous oxide interlayers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fadlallah, Mohamed M.; Eckern, Ulrich; Schwingenschlögl, Udo</p> <p>2016-06-01</p> <p>The <span class="hlt">electronic</span> <span class="hlt">transport</span> through Au–(Cu2O)n–Au junctions is investigated using first-principles calculations and the nonequilibrium Green’s function method. The effect of varying the thickness (i.e., n) is studied as well as that of point defects and anion substitution. For all Cu2O thicknesses the conductance is more enhanced by bulk-like (in contrast to near-interface) defects, with the exception of O vacancies and Cl substitutional defects. A similar transmission behavior results from Cu deficiency and N substitution, as well as from Cl substitution and N interstitials for thick Cu2O junctions. In agreement with recent experimental observations, it is found that N and Cl doping enhances the conductance. A Frenkel defect, i.e., a superposition of an O interstitial and O substitutional defect, leads to a remarkably high conductance. From the analysis of the defect formation energies, Cu vacancies are found to be particularly stable, in agreement with earlier experimental and theoretical work.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <center> <div class="footer-extlink text-muted"><small>Some links on this page may take you to non-federal websites. 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